posts-go/docs/2022-07-10-bootstrap-go.html

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<h2>
<a href="index.html"><code>~</code></a>
</h2>
<h1>
<a
id="user-content-bootstrap-go"
class="anchor"
aria-hidden="true"
href="#bootstrap-go"
><span aria-hidden="true" class="octicon octicon-link"></span></a
>Bootstrap Go
</h1>
<p>
It is hard to write bootstrap tool to quickly create Go service. So I
write this guide instead. This is a quick checklist for me every damn time
I need to write a Go service from scratch. Also, this is my personal
opinion, so feel free to comment.
</p>
<h2>
<a
id="user-content-structure"
class="anchor"
aria-hidden="true"
href="#structure"
><span aria-hidden="true" class="octicon octicon-link"></span></a
>Structure
</h2>
<div class="highlight highlight-text-adblock">
<pre>
main.go
internal
business
http
handler.go
service.go
models.go
grpc
handler.go
models.go
consumer
handler.go
service.go
models.go
service.go
repository.go
models.go</pre
>
</div>
<p>
All business codes are inside <code>internal</code>. Each business has a
different directory <code>business</code>.
</p>
<p>
Inside each business, there are 2 handlers: <code>http</code>,
<code>grpc</code>:
</p>
<ul>
<li>
<code>http</code> is for public APIs (Android, iOS, ... are clients).
</li>
<li>
<code>grpc</code> is for internal APIs (other services are clients).
</li>
<li>
<code>consumer</code> is for consuming messages from queue (Kafka,
RabbitMQ, ...).
</li>
</ul>
<p>
For each handler, there are usually 3 layers: <code>handler</code>,
<code>service</code>, <code>repository</code>:
</p>
<ul>
<li>
<code>handler</code> interacts directly with gRPC, REST or consumer
using specific codes (cookies, ...) In case gRPC, there are frameworks
outside handle for us so we can write business/logic codes here too. But
remember, gRPC only.
</li>
<li>
<code>service</code> is where we write business/logic codes, and only
business/logic codes is written here.
</li>
<li>
<code>repository</code> is where we write codes which interacts with
database/cache like MySQL, Redis, ...
</li>
<li>
<code>models</code> is where we put all request, response, data models.
</li>
</ul>
<p>Location:</p>
<ul>
<li>
<code>handler</code> must exist inside <code>grpc</code>,
<code>http</code>, <code>consumer</code>.
</li>
<li>
<code>service</code>, <code>models</code> can exist directly inside of
<code>business</code> if both <code>grpc</code>, <code>http</code>,
<code>consumer</code> has same business/logic.
</li>
<li>
<code>repository</code> should be placed directly inside of
<code>business</code>.
</li>
</ul>
<h2>
<a
id="user-content-do-not-repeat"
class="anchor"
aria-hidden="true"
href="#do-not-repeat"
><span aria-hidden="true" class="octicon octicon-link"></span></a
>Do not repeat!
</h2>
<p>If we have too many services, some of the logic will be overlapped.</p>
<p>
For example, service A and service B both need to make POST call API to
service C. If service A and service B both have libs to call service C to
do that API, we need to move the libs to some common pkg libs. So in the
future, service D which needs to call C will not need to copy libs to
handle service C api but only need to import from common pkg libs.
</p>
<p>
Another bad practice is adapter service. No need to write a new service if
what we need is just common pkg libs.
</p>
<h2>
<a
id="user-content-taste-on-style-guide"
class="anchor"
aria-hidden="true"
href="#taste-on-style-guide"
><span aria-hidden="true" class="octicon octicon-link"></span></a
>Taste on style guide
</h2>
<h3>
<a
id="user-content-stop-using-global-var"
class="anchor"
aria-hidden="true"
href="#stop-using-global-var"
><span aria-hidden="true" class="octicon octicon-link"></span></a
>Stop using global var
</h3>
<p>
If I see someone using global var, I swear I will shoot them twice in the
face.
</p>
<p>Why?</p>
<ul>
<li>Can not write unit test.</li>
<li>Is not thread safe.</li>
</ul>
<h3>
<a
id="user-content-use-functional-options-but-dont-overuse-it"
class="anchor"
aria-hidden="true"
href="#use-functional-options-but-dont-overuse-it"
><span aria-hidden="true" class="octicon octicon-link"></span></a
>Use functional options, but don't overuse it!
</h3>
<p>
For simple struct with 1 or 2 fields, no need to use functional options.
</p>
<p>
<a href="https://go.dev/play/p/0XnOLiHuoz3" rel="nofollow">Example</a>:
</p>
<div class="highlight highlight-source-go">
<pre><span class="pl-k">func</span> <span class="pl-en">main</span>() {
<span class="pl-s1">s</span> <span class="pl-c1">:=</span> <span class="pl-en">NewS</span>(<span class="pl-en">WithA</span>(<span class="pl-c1">1</span>), <span class="pl-en">WithB</span>(<span class="pl-s">"b"</span>))
<span class="pl-s1">fmt</span>.<span class="pl-en">Printf</span>(<span class="pl-s">"%+v<span class="pl-cce">\n</span>"</span>, <span class="pl-s1">s</span>)
}
<span class="pl-k">type</span> <span class="pl-smi">S</span> <span class="pl-k">struct</span> {
<span class="pl-c1">fieldA</span> <span class="pl-smi">int</span>
<span class="pl-c1">fieldB</span> <span class="pl-smi">string</span>
}
<span class="pl-k">type</span> <span class="pl-smi">OptionS</span> <span class="pl-k">func</span>(<span class="pl-s1">s</span> <span class="pl-c1">*</span><span class="pl-smi">S</span>)
<span class="pl-k">func</span> <span class="pl-en">WithA</span>(<span class="pl-s1">a</span> <span class="pl-smi">int</span>) <span class="pl-smi">OptionS</span> {
<span class="pl-k">return</span> <span class="pl-k">func</span>(<span class="pl-s1">s</span> <span class="pl-c1">*</span><span class="pl-smi">S</span>) {
<span class="pl-s1">s</span>.<span class="pl-c1">fieldA</span> <span class="pl-c1">=</span> <span class="pl-s1">a</span>
}
}
<span class="pl-k">func</span> <span class="pl-en">WithB</span>(<span class="pl-s1">b</span> <span class="pl-smi">string</span>) <span class="pl-smi">OptionS</span> {
<span class="pl-k">return</span> <span class="pl-k">func</span>(<span class="pl-s1">s</span> <span class="pl-c1">*</span><span class="pl-smi">S</span>) {
<span class="pl-s1">s</span>.<span class="pl-c1">fieldB</span> <span class="pl-c1">=</span> <span class="pl-s1">b</span>
}
}
<span class="pl-k">func</span> <span class="pl-en">NewS</span>(<span class="pl-s1">opts</span> <span class="pl-c1">...</span><span class="pl-smi">OptionS</span>) <span class="pl-c1">*</span><span class="pl-smi">S</span> {
<span class="pl-s1">s</span> <span class="pl-c1">:=</span> <span class="pl-c1">&amp;</span><span class="pl-smi">S</span>{}
<span class="pl-k">for</span> <span class="pl-s1">_</span>, <span class="pl-s1">opt</span> <span class="pl-c1">:=</span> <span class="pl-k">range</span> <span class="pl-s1">opts</span> {
<span class="pl-en">opt</span>(<span class="pl-s1">s</span>)
}
<span class="pl-k">return</span> <span class="pl-s1">s</span>
}</pre>
</div>
<p>
In above example, I construct <code>s</code> with <code>WithA</code> and
<code>WithB</code> option. No need to pass direct field inside
<code>s</code>.
</p>
<h3>
<a
id="user-content-use-errgroup-as-much-as-possible"
class="anchor"
aria-hidden="true"
href="#use-errgroup-as-much-as-possible"
><span aria-hidden="true" class="octicon octicon-link"></span></a
>Use
<a href="https://pkg.go.dev/golang.org/x/sync/errgroup" rel="nofollow"
>errgroup</a
>
as much as possible
</h3>
<p>
If business logic involves calling too many APIs, but they are not depend
on each other. We can fire them parallel :)
</p>
<p>
Personally, I prefer <code>errgroup</code> to <code>WaitGroup</code> (<a
href="https://pkg.go.dev/sync#WaitGroup"
rel="nofollow"
>https://pkg.go.dev/sync#WaitGroup</a
>). Because I always need deal with error. Be super careful with
<code>egCtx</code>, should use this instead of parent
<code>ctx</code> inside <code>eg.Go</code>.
</p>
<p>Example:</p>
<div class="highlight highlight-source-go">
<pre><span class="pl-s1">eg</span>, <span class="pl-s1">egCtx</span> <span class="pl-c1">:=</span> <span class="pl-s1">errgroup</span>.<span class="pl-en">WithContext</span>(<span class="pl-s1">ctx</span>)
<span class="pl-s1">eg</span>.<span class="pl-en">Go</span>(<span class="pl-k">func</span>() <span class="pl-smi">error</span> {
<span class="pl-c">// Do some thing</span>
<span class="pl-k">return</span> <span class="pl-c1">nil</span>
})
<span class="pl-s1">eg</span>.<span class="pl-en">Go</span>(<span class="pl-k">func</span>() <span class="pl-smi">error</span> {
<span class="pl-c">// Do other thing</span>
<span class="pl-k">return</span> <span class="pl-c1">nil</span>
})
<span class="pl-k">if</span> <span class="pl-s1">err</span> <span class="pl-c1">:=</span> <span class="pl-s1">eg</span>.<span class="pl-en">Wait</span>(); <span class="pl-s1">err</span> <span class="pl-c1">!=</span> <span class="pl-c1">nil</span> {
<span class="pl-c">// Handle error</span>
}</pre>
</div>
<h3>
<a
id="user-content-use-semaphore-when-need-to-implement-workerpool"
class="anchor"
aria-hidden="true"
href="#use-semaphore-when-need-to-implement-workerpool"
><span aria-hidden="true" class="octicon octicon-link"></span></a
>Use
<a href="https://pkg.go.dev/golang.org/x/sync/semaphore" rel="nofollow"
>semaphore</a
>
when need to implement WorkerPool
</h3>
<p>
Please don't use external libs for WorkerPool, I don't want to deal with
dependency hell.
</p>
<h3>
<a
id="user-content-use-syncpool-when-need-to-reuse-object-mainly-for-bytesbuffer"
class="anchor"
aria-hidden="true"
href="#use-syncpool-when-need-to-reuse-object-mainly-for-bytesbuffer"
><span aria-hidden="true" class="octicon octicon-link"></span></a
>Use
<a href="https://pkg.go.dev/sync#Pool" rel="nofollow">sync.Pool</a> when
need to reuse object, mainly for <code>bytes.Buffer</code>
</h3>
<p>Example:</p>
<div class="highlight highlight-source-go">
<pre><span class="pl-k">var</span> <span class="pl-s1">bufPool</span> <span class="pl-c1">=</span> sync.<span class="pl-smi">Pool</span>{
<span class="pl-c1">New</span>: <span class="pl-k">func</span>() <span class="pl-smi">any</span> {
<span class="pl-k">return</span> <span class="pl-en">new</span>(bytes.<span class="pl-smi">Buffer</span>)
},
}
<span class="pl-k">func</span> <span class="pl-en">MarshalWithoutEscapeHTML</span>(<span class="pl-s1">v</span> <span class="pl-smi">any</span>) ([]<span class="pl-smi">byte</span>, <span class="pl-smi">error</span>) {
<span class="pl-s1">b</span>, <span class="pl-s1">ok</span> <span class="pl-c1">:=</span> <span class="pl-s1">bufPool</span>.<span class="pl-en">Get</span>().(<span class="pl-c1">*</span>bytes.<span class="pl-smi">Buffer</span>)
<span class="pl-k">if</span> <span class="pl-c1">!</span><span class="pl-s1">ok</span> {
<span class="pl-k">return</span> <span class="pl-c1">nil</span>, <span class="pl-s1">ErrBufPoolNotBytesBuffer</span>
}
<span class="pl-s1">b</span>.<span class="pl-en">Reset</span>()
<span class="pl-k">defer</span> <span class="pl-s1">bufPool</span>.<span class="pl-en">Put</span>(<span class="pl-s1">b</span>)
<span class="pl-s1">encoder</span> <span class="pl-c1">:=</span> <span class="pl-s1">json</span>.<span class="pl-en">NewEncoder</span>(<span class="pl-s1">b</span>)
<span class="pl-s1">encoder</span>.<span class="pl-en">SetEscapeHTML</span>(<span class="pl-c1">false</span>)
<span class="pl-k">if</span> <span class="pl-s1">err</span> <span class="pl-c1">:=</span> <span class="pl-s1">encoder</span>.<span class="pl-en">Encode</span>(<span class="pl-s1">v</span>); <span class="pl-s1">err</span> <span class="pl-c1">!=</span> <span class="pl-c1">nil</span> {
<span class="pl-k">return</span> <span class="pl-c1">nil</span>, <span class="pl-s1">err</span>
}
<span class="pl-s1">result</span> <span class="pl-c1">:=</span> <span class="pl-en">make</span>([]<span class="pl-smi">byte</span>, <span class="pl-s1">b</span>.<span class="pl-en">Len</span>())
<span class="pl-en">copy</span>(<span class="pl-s1">result</span>, <span class="pl-s1">b</span>.<span class="pl-en">Bytes</span>())
<span class="pl-k">return</span> <span class="pl-s1">result</span>, <span class="pl-c1">nil</span>
}</pre>
</div>
<h2>
<a
id="user-content-external-libs"
class="anchor"
aria-hidden="true"
href="#external-libs"
><span aria-hidden="true" class="octicon octicon-link"></span></a
>External libs
</h2>
<h3>
<a
id="user-content-no-need-vendor"
class="anchor"
aria-hidden="true"
href="#no-need-vendor"
><span aria-hidden="true" class="octicon octicon-link"></span></a
>No need <code>vendor</code>
</h3>
<p>
Only need if you need something from <code>vendor</code>, to generate mock
or something else.
</p>
<h3>
<a
id="user-content-use-buildgo-to-include-build-tools-in-gomod"
class="anchor"
aria-hidden="true"
href="#use-buildgo-to-include-build-tools-in-gomod"
><span aria-hidden="true" class="octicon octicon-link"></span></a
>Use <code>build.go</code> to include build tools in go.mod
</h3>
<p>To easily control version of build tools.</p>
<p>For example <code>build.go</code>:</p>
<div class="highlight highlight-source-go">
<pre><span class="pl-c">//go:build tools</span>
<span class="pl-c">// +build tools</span>
<span class="pl-k">package</span> main
<span class="pl-k">import</span> (
_ <span class="pl-s">"github.com/golang/protobuf/protoc-gen-go"</span>
)</pre>
</div>
<p>And then in <code>Makefile</code>:</p>
<div class="highlight highlight-source-makefile">
<pre><span class="pl-en">build</span>:
go install github.com/golang/protobuf/protoc-gen-go</pre>
</div>
<p>
We always get the version of build tools in <code>go.mod</code> each time
we install it. Future contributors will not cry anymore.
</p>
<h3>
<a
id="user-content-dont-use-cli-libs-spf13cobra-urfavecli-just-for-go-service"
class="anchor"
aria-hidden="true"
href="#dont-use-cli-libs-spf13cobra-urfavecli-just-for-go-service"
><span aria-hidden="true" class="octicon octicon-link"></span></a
>Don't use cli libs (<a href="https://github.com/spf13/cobra"
>spf13/cobra</a
>, <a href="https://github.com/urfave/cli">urfave/cli</a>) just for Go
service
</h3>
<p>
What is the point to pass many params (<code>do-it</code>,
<code>--abc</code>, <code>--xyz</code>) when what we only need is start
service?
</p>
<p>
In my case, service starts with only config, and config should be read
from file or environment like
<a href="https://12factor.net/" rel="nofollow">The Twelve Factors</a>
guide.
</p>
<h3>
<a
id="user-content-dont-use-grpc-ecosystemgrpc-gateway"
class="anchor"
aria-hidden="true"
href="#dont-use-grpc-ecosystemgrpc-gateway"
><span aria-hidden="true" class="octicon octicon-link"></span></a
>Don't use
<a href="https://github.com/grpc-ecosystem/grpc-gateway"
>grpc-ecosystem/grpc-gateway</a
>
</h3>
<p>Just don't.</p>
<p>
Use
<a href="https://github.com/protocolbuffers/protobuf-go"
>protocolbuffers/protobuf-go</a
>, <a href="https://github.com/grpc/grpc-go">grpc/grpc-go</a> for gRPC.
</p>
<p>
Write 1 for both gRPC, REST sounds good, but in the end, it is not worth
it.
</p>
<h3>
<a
id="user-content-dont-use-uberprototool-use-bufbuildbuf"
class="anchor"
aria-hidden="true"
href="#dont-use-uberprototool-use-bufbuildbuf"
><span aria-hidden="true" class="octicon octicon-link"></span></a
>Don't use <a href="https://github.com/uber/prototool">uber/prototool</a>,
use <a href="https://github.com/bufbuild/buf">bufbuild/buf</a>
</h3>
<p>
prototool is deprecated, and buf can generate, lint, format as good as
prototool.
</p>
<h3>
<a
id="user-content-use-gin-gonicgin-for-rest"
class="anchor"
aria-hidden="true"
href="#use-gin-gonicgin-for-rest"
><span aria-hidden="true" class="octicon octicon-link"></span></a
>Use <a href="https://github.com/gin-gonic/gin">gin-gonic/gin</a> for
REST.
</h3>
<p>With <code>c *gin.Context</code>:</p>
<ul>
<li>
Don't use <code>c</code> when passing context, use
<code>c.Request.Context()</code> instead.
</li>
<li>
Don't use <code>c.Request.URL.Path</code>, use
<code>c.FullPath()</code> instead.
</li>
</ul>
<p>Remember to free resources after parse multipart form:</p>
<div class="highlight highlight-source-go">
<pre><span class="pl-k">defer</span> <span class="pl-k">func</span>() {
<span class="pl-k">if</span> <span class="pl-s1">err</span> <span class="pl-c1">:=</span> <span class="pl-s1">c</span>.<span class="pl-c1">Request</span>.<span class="pl-c1">MultipartForm</span>.<span class="pl-en">RemoveAll</span>(); <span class="pl-s1">err</span> <span class="pl-c1">!=</span> <span class="pl-c1">nil</span> {
<span class="pl-s1">fmt</span>.<span class="pl-en">Println</span>(<span class="pl-s1">err</span>)
}
}()</pre>
</div>
<h3>
<a
id="user-content-if-you-want-log-just-use-uber-gozap"
class="anchor"
aria-hidden="true"
href="#if-you-want-log-just-use-uber-gozap"
><span aria-hidden="true" class="octicon octicon-link"></span></a
>If you want log, just use
<a href="https://github.com/uber-go/zap">uber-go/zap</a>
</h3>
<p>It is fast!</p>
<ul>
<li>
Don't overuse <code>func (*Logger) With</code>. Because if log line is
too long, there is a possibility that we can lost it.
</li>
<li>
Use <code>MarshalLogObject</code> when we need to hide some field of
object when log (field is long or has sensitive value)
</li>
<li>
Don't use <code>Panic</code>. Use <code>Fatal</code> for errors when
start service to check dependencies. If you really need panic level, use
<code>DPanic</code>.
</li>
<li>If doubt, use <code>zap.Any</code>.</li>
<li>
Use <code>contextID</code> or <code>traceID</code> in every log lines
for easily debug.
</li>
</ul>
<h3>
<a
id="user-content-to-read-config-use-spf13viper"
class="anchor"
aria-hidden="true"
href="#to-read-config-use-spf13viper"
><span aria-hidden="true" class="octicon octicon-link"></span></a
>To read config, use
<a href="https://github.com/spf13/viper">spf13/viper</a>
</h3>
<p>
Only init config in main or cmd layer. Do not use
<code>viper.Get...</code> in business layer or inside business layer.
</p>
<p>Why?</p>
<ul>
<li>Hard to mock and test</li>
<li>Put all config in single place for easily tracking</li>
</ul>
<p>
Also, be careful if config value is empty. You should decide to continue
or stop the service if there is empty config.
</p>
<h3>
<a
id="user-content-dont-overuse-orm-libs-no-need-to-handle-another-layer-above-sql"
class="anchor"
aria-hidden="true"
href="#dont-overuse-orm-libs-no-need-to-handle-another-layer-above-sql"
><span aria-hidden="true" class="octicon octicon-link"></span></a
>Don't overuse ORM libs, no need to handle another layer above SQL.
</h3>
<p>
Each ORM libs has each different syntax. To learn and use those libs
correctly is time consuming. So just stick to plain SQL. It is easier to
debug when something is wrong.
</p>
<p>
Also please use
<a href="https://go.dev/doc/database/prepared-statements" rel="nofollow"
>prepared statement</a
>
as much as possible. Idealy, we should init all prepared statement when we
init database connection to cached it, not create it every time we need
it.
</p>
<p>
But <code>database/sql</code> has its own limit. For example, it is hard
to get primary key after insert/update. So may be you want to use ORM for
those cases. I hear that
<a href="https://github.com/go-gorm/gorm">go-gorm/gorm</a>,
<a href="https://github.com/ent/ent">ent/ent</a> is good.
</p>
<h3>
<a
id="user-content-connect-redis-with-redisgo-redis"
class="anchor"
aria-hidden="true"
href="#connect-redis-with-redisgo-redis"
><span aria-hidden="true" class="octicon octicon-link"></span></a
>Connect Redis with
<a href="https://github.com/redis/go-redis">redis/go-redis</a>
</h3>
<p>
Be careful when use
<a href="https://redis.io/commands/hgetall/" rel="nofollow">HGETALL</a>.
If key not found, empty data will be returned not nil error. See
<a href="https://github.com/redis/go-redis/issues/1668"
>redis/go-redis/issues/1668</a
>
</p>
<p>
Use
<a
href="https://redis.uptrace.dev/guide/go-redis-pipelines.html"
rel="nofollow"
>Pipelines</a
>
for:
</p>
<ul>
<li>HSET and EXPIRE in 1 command.</li>
<li>Multiple GET in 1 command.</li>
</ul>
<p>
Prefer to use <code>Pipelined</code> instead of <code>Pipeline</code>.
Inside <code>Pipelined</code>, please return <code>redis.Cmder</code> for
each command.
</p>
<p>Example:</p>
<div class="highlight highlight-source-go">
<pre><span class="pl-k">func</span> (<span class="pl-s1">c</span> <span class="pl-c1">*</span><span class="pl-smi">client</span>) <span class="pl-en">HSetWithExpire</span>(<span class="pl-s1">ctx</span> context.<span class="pl-smi">Context</span>, <span class="pl-s1">key</span> <span class="pl-smi">string</span>, <span class="pl-s1">values</span> []<span class="pl-smi">any</span>, <span class="pl-s1">expired</span> time.<span class="pl-smi">Duration</span>) <span class="pl-smi">error</span> {
<span class="pl-s1">cmds</span> <span class="pl-c1">:=</span> <span class="pl-en">make</span>([]redis.<span class="pl-smi">Cmder</span>, <span class="pl-c1">2</span>)
<span class="pl-k">if</span> <span class="pl-s1">_</span>, <span class="pl-s1">err</span> <span class="pl-c1">:=</span> <span class="pl-s1">c</span>.<span class="pl-en">Pipelined</span>(<span class="pl-s1">ctx</span>, <span class="pl-k">func</span>(<span class="pl-s1">pipe</span> redis.<span class="pl-smi">Pipeliner</span>) <span class="pl-smi">error</span> {
<span class="pl-s1">cmds</span>[<span class="pl-c1">0</span>] <span class="pl-c1">=</span> <span class="pl-s1">pipe</span>.<span class="pl-en">HSet</span>(<span class="pl-s1">ctx</span>, <span class="pl-s1">key</span>, <span class="pl-s1">values</span><span class="pl-c1">...</span>)
<span class="pl-k">if</span> <span class="pl-s1">expired</span> <span class="pl-c1">&gt;</span> <span class="pl-c1">0</span> {
<span class="pl-s1">cmds</span>[<span class="pl-c1">1</span>] <span class="pl-c1">=</span> <span class="pl-s1">pipe</span>.<span class="pl-en">Expire</span>(<span class="pl-s1">ctx</span>, <span class="pl-s1">key</span>, <span class="pl-s1">expired</span>)
}
<span class="pl-k">return</span> <span class="pl-c1">nil</span>
}); <span class="pl-s1">err</span> <span class="pl-c1">!=</span> <span class="pl-c1">nil</span> {
<span class="pl-k">return</span> <span class="pl-s1">err</span>
}
<span class="pl-k">for</span> <span class="pl-s1">_</span>, <span class="pl-s1">cmd</span> <span class="pl-c1">:=</span> <span class="pl-k">range</span> <span class="pl-s1">cmds</span> {
<span class="pl-k">if</span> <span class="pl-s1">cmd</span> <span class="pl-c1">==</span> <span class="pl-c1">nil</span> {
<span class="pl-k">continue</span>
}
<span class="pl-k">if</span> <span class="pl-s1">err</span> <span class="pl-c1">:=</span> <span class="pl-s1">cmd</span>.<span class="pl-en">Err</span>(); <span class="pl-s1">err</span> <span class="pl-c1">!=</span> <span class="pl-c1">nil</span> {
<span class="pl-k">return</span> <span class="pl-s1">err</span>
}
}
<span class="pl-k">return</span> <span class="pl-c1">nil</span>
}</pre>
</div>
<p>Remember to config:</p>
<ul>
<li><code>ReadTimeout</code>, <code>WriteTimeout</code></li>
</ul>
<h3>
<a
id="user-content-connect-mysql-with-go-sql-drivermysql"
class="anchor"
aria-hidden="true"
href="#connect-mysql-with-go-sql-drivermysql"
><span aria-hidden="true" class="octicon octicon-link"></span></a
>Connect MySQL with
<a href="https://github.com/go-sql-driver/mysql">go-sql-driver/mysql</a>
</h3>
<p>Remember to config:</p>
<ul>
<li><code>SetConnMaxLifetime</code></li>
<li><code>SetMaxOpenConns</code></li>
<li><code>SetMaxIdleConns</code></li>
<li><code>ParseTime</code> to true.</li>
<li><code>Loc</code> to <code>time.UTC</code>.</li>
<li><code>CheckConnLiveness</code> to true.</li>
<li><code>ReadTimeout</code>, <code>WriteTimeout</code></li>
</ul>
<h3>
<a
id="user-content-connect-sqlite-with-moderncorgsqlite"
class="anchor"
aria-hidden="true"
href="#connect-sqlite-with-moderncorgsqlite"
><span aria-hidden="true" class="octicon octicon-link"></span></a
>Connect SQLite with
<a href="https://gitlab.com/cznic/sqlite" rel="nofollow"
>modernc.org/sqlite</a
>
</h3>
<p>Remember to config:</p>
<ul>
<li>Write-Ahead Logging: <code>PRAGMA journal_mode=WAL</code></li>
<li>
Disable connections pool with <code>SetMaxOpenConns</code> sets to 1
</li>
</ul>
<p>
Don't use
<a href="https://github.com/mattn/go-sqlite3">mattn/go-sqlite3</a>, it's
required <code>CGO_ENABLED</code>.
</p>
<h3>
<a
id="user-content-connect-kafka-with-shopifysarama"
class="anchor"
aria-hidden="true"
href="#connect-kafka-with-shopifysarama"
><span aria-hidden="true" class="octicon octicon-link"></span></a
>Connect Kafka with
<a href="https://github.com/Shopify/sarama">Shopify/sarama</a>
</h3>
<p>
Don't use
<a href="https://github.com/confluentinc/confluent-kafka-go"
>confluentinc/confluent-kafka-go</a
>, it's required <code>CGO_ENABLED</code>.
</p>
<h3>
<a
id="user-content-if-you-want-test-just-use-stretchrtestify"
class="anchor"
aria-hidden="true"
href="#if-you-want-test-just-use-stretchrtestify"
><span aria-hidden="true" class="octicon octicon-link"></span></a
>If you want test, just use
<a href="https://github.com/stretchr/testify">stretchr/testify</a>.
</h3>
<p>
It is easy to write a suite test, thanks to testify. Also, for mocking,
there are many options out there. Pick 1 then sleep peacefully.
</p>
<h3>
<a
id="user-content-if-need-to-mock-choose-matryermoq-or-ubermock"
class="anchor"
aria-hidden="true"
href="#if-need-to-mock-choose-matryermoq-or-ubermock"
><span aria-hidden="true" class="octicon octicon-link"></span></a
>If need to mock, choose
<a href="https://github.com/matryer/moq">matryer/moq</a> or
<a href="https://github.com/uber/mock">uber/mock</a>
</h3>
<p>
The first is easy to use but not powerful as the later. If you want to
make sure mock func is called with correct times, use the later.
</p>
<p>Example with <code>matryer/moq</code>:</p>
<div class="highlight highlight-source-go">
<pre><span class="pl-c">// Only gen mock if source code file is newer than mock file</span>
<span class="pl-c">// https://jonwillia.ms/2019/12/22/conditional-gomock-mockgen</span>
<span class="pl-c">//go:generate sh -c "test service_mock_generated.go -nt $GOFILE &amp;&amp; exit 0; moq -rm -out service_mock_generated.go . Service"</span></pre>
</div>
<h3>
<a
id="user-content-be-careful-with-spf13cast"
class="anchor"
aria-hidden="true"
href="#be-careful-with-spf13cast"
><span aria-hidden="true" class="octicon octicon-link"></span></a
>Be careful with <a href="https://github.com/spf13/cast">spf13/cast</a>
</h3>
<p>Don't cast proto enum:</p>
<div class="highlight highlight-source-go">
<pre><span class="pl-c">// Bad</span>
<span class="pl-s1">a</span> <span class="pl-c1">:=</span> <span class="pl-s1">cast</span>.<span class="pl-en">ToInt32</span>(<span class="pl-s1">servicev1</span>.<span class="pl-c1">ReasonCode_ABC</span>)
<span class="pl-c">// Good</span>
<span class="pl-s1">a</span> <span class="pl-c1">:=</span> <span class="pl-en">int32</span>(<span class="pl-s1">servicev1</span>.<span class="pl-c1">ReasonCode_ABC</span>)</pre>
</div>
<h3>
<a
id="user-content-use-stringer-if-you-want-your-type-enum-can-be-print-as-string"
class="anchor"
aria-hidden="true"
href="#use-stringer-if-you-want-your-type-enum-can-be-print-as-string"
><span aria-hidden="true" class="octicon octicon-link"></span></a
>Use
<a
href="https://pkg.go.dev/golang.org/x/tools/cmd/stringer"
rel="nofollow"
>stringer</a
>
if you want your type enum can be print as string
</h3>
<div class="highlight highlight-source-go">
<pre><span class="pl-k">type</span> <span class="pl-smi">Drink</span> <span class="pl-smi">int</span>
<span class="pl-k">const</span> (
<span class="pl-s1">Beer</span> <span class="pl-smi">Drink</span> <span class="pl-c1">=</span> <span class="pl-s1">iota</span>
<span class="pl-s1">Water</span>
<span class="pl-s1">OrangeJuice</span>
)</pre>
</div>
<div class="highlight highlight-source-shell">
<pre>go install golang.org/x/tools/cmd/stringer@latest
<span class="pl-c"><span class="pl-c">#</span> Run inside directory which contains Drink</span>
stringer -type=Drink</pre>
</div>
<h3>
<a
id="user-content-dont-waste-your-time-rewrite-rate-limiter-if-your-use-case-is-simple-use-rate-or-go-redisredis_rate"
class="anchor"
aria-hidden="true"
href="#dont-waste-your-time-rewrite-rate-limiter-if-your-use-case-is-simple-use-rate-or-go-redisredis_rate"
><span aria-hidden="true" class="octicon octicon-link"></span></a
>Don't waste your time rewrite rate limiter if your use case is simple,
use
<a href="https://pkg.go.dev/golang.org/x/time/rate" rel="nofollow"
>rate</a
>
or
<a href="https://github.com/go-redis/redis_rate">go-redis/redis_rate</a>
</h3>
<p>
<strong>rate</strong> if you want rate limiter locally in your single
instance of service. <strong>redis_rate</strong> if you want rate limiter
distributed across all your instances of service.
</p>
<h3>
<a
id="user-content-replace-go-fmt-goimports-with-mvdangofumpt"
class="anchor"
aria-hidden="true"
href="#replace-go-fmt-goimports-with-mvdangofumpt"
><span aria-hidden="true" class="octicon octicon-link"></span></a
>Replace <code>go fmt</code>, <code>goimports</code> with
<a href="https://github.com/mvdan/gofumpt">mvdan/gofumpt</a>.
</h3>
<p><code>gofumpt</code> provides more rules when format Go codes.</p>
<h3>
<a
id="user-content-use-golangcigolangci-lint"
class="anchor"
aria-hidden="true"
href="#use-golangcigolangci-lint"
><span aria-hidden="true" class="octicon octicon-link"></span></a
>Use
<a href="https://github.com/golangci/golangci-lint"
>golangci/golangci-lint</a
>.
</h3>
<p>No need to say more. Lint or get the f out!</p>
<p>
If you get <code>fieldalignment</code> error, use
<a
href="https://pkg.go.dev/golang.org/x/tools/go/analysis/passes/fieldalignment"
rel="nofollow"
>fieldalignment</a
>
to fix them.
</p>
<div class="highlight highlight-source-shell">
<pre><span class="pl-c"><span class="pl-c">#</span> Install</span>
go install golang.org/x/tools/go/analysis/passes/fieldalignment/cmd/fieldalignment@latest
<span class="pl-c"><span class="pl-c">#</span> Fix</span>
fieldalignment -fix ./internal/business/<span class="pl-k">*</span>.go</pre>
</div>
<h2>
<a
id="user-content-snippetscript"
class="anchor"
aria-hidden="true"
href="#snippetscript"
><span aria-hidden="true" class="octicon octicon-link"></span></a
>Snippet/script
</h2>
<p>Change import:</p>
<div class="highlight highlight-source-shell">
<pre>gofmt -w -r <span class="pl-s"><span class="pl-pds">'</span>"github.com/Sirupsen/logrus" -&gt; "github.com/sirupsen/logrus"<span class="pl-pds">'</span></span> <span class="pl-k">*</span>.go</pre>
</div>
<p>Cleanup if storage is full:</p>
<div class="highlight highlight-source-shell">
<pre>go clean -cache -testcache -modcache -fuzzcache -x</pre>
</div>
<h2>
<a
id="user-content-thanks"
class="anchor"
aria-hidden="true"
href="#thanks"
><span aria-hidden="true" class="octicon octicon-link"></span></a
>Thanks
</h2>
<ul>
<li>
<a
href="https://dave.cheney.net/2014/10/17/functional-options-for-friendly-apis"
rel="nofollow"
>Functional options for friendly APIs</a
>
</li>
<li>
<a
href="https://abhinavg.net/2022/12/06/designing-go-libraries/"
rel="nofollow"
>Designing Go Libraries: The Talk: The Article</a
>
</li>
<li>
<a href="https://github.com/uber-go/guide/blob/master/style.md"
>Uber Go Style Guide</a
>
</li>
<li>
<a href="https://google.github.io/styleguide/go/index" rel="nofollow"
>Google Go Style</a
>
</li>
<li>
<a
href="https://github.blog/2020-05-20-three-bugs-in-the-go-mysql-driver/"
rel="nofollow"
>Three bugs in the Go MySQL Driver</a
>
</li>
<li>
<a href="https://mtlynch.io/notes/picoshare-perf/" rel="nofollow"
>Fixing Memory Exhaustion Bugs in My Golang Web App</a
>
</li>
<li>
<a
href="https://www.commonfate.io/blog/prevent-logging-secrets-in-go-by-using-custom-types"
rel="nofollow"
>Prevent Logging Secrets in Go by Using Custom Types</a
>
</li>
<li>
<a
href="https://jonwillia.ms/2019/12/22/conditional-gomock-mockgen"
rel="nofollow"
>Speed Up GoMock with Conditional Generation</a
>
</li>
<li>
<a
href="https://turriate.com/articles/making-sqlite-faster-in-go"
rel="nofollow"
>Making SQLite faster in Go</a
>
</li>
</ul>
<div>
Feel free to ask me via
<a href="mailto:hauvipapro+posts@gmail.com">email</a> or
<a rel="me" href="https://hachyderm.io/@haunguyen">Mastodon</a>. Source
code is available on
<a href="https://github.com/haunt98/posts-go">GitHub</a>
</div>
</body>
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