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Enhancements: configurable database file path, default port, and optimised Docker image #109

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Oct 31, 2017
Merged

Enhancements: configurable database file path, default port, and optimised Docker image #109

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394db4a
Allow database file path to be configured
MrSaints Oct 27, 2017
bfb7921
Refactor `Dockerfile` for better caching, and to minimise final image…
MrSaints Oct 27, 2017
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7 changes: 7 additions & 0 deletions .dockerignore
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@@ -0,0 +1,7 @@
*.db
*.md
.dockerfile
.editorconfig
.gitignore
Dockerfile
example/
39 changes: 26 additions & 13 deletions Dockerfile
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@@ -1,20 +1,33 @@
# golang1.8.1 base image
FROM golang:1.8.1
# Build backend
FROM golang:1.8.1 as backend-build

# copy source
COPY . /go/src/commento
WORKDIR /go/src/commento

# build backend
RUN go get -v .
RUN go install .
RUN go build -ldflags '-linkmode external -extldflags -static -w'
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Not a review comment, just curious: what does this do? I haven't been writing Go long enough ^^

Searching tells me -linkmode external can be used to load go variables at compile time. Is that the reasoning?

-static is static linking, I can tell. -w is some kind of executable size reduction technique from what I read (add -s as well?).

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@MrSaints MrSaints Oct 30, 2017 •
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The reason I went with this versus a standard go build is because I wanted to build a static binary from the golang Docker image, and still be able to use it in alpine. There are a couple of problems if we rely on the former.

One of which is your project's use of mattn/go-sqlite3. It is a cgo package, not a Go package. Your project however, is in Go. So we have situation where we need a combination of Go, and non-Go code to be in the final executable without dynamic libraries. So, -linkmode external simply tells cmd/linker to invoke the host linker (often gcc) to combine your Go code (compiled by Go to an object file go.o, but not processed any further) with your non-Go code.

It is also possibly using cgo from the net library (see https://golang.org/pkg/net/#hdr-Name_Resolution).

Everything after -extldflags are flags for gcc (-w to suppress warnings IIRC).

TL;DR: I just want a static binary. If I relied on the standard go build, we'd get an 'output' that relies on dynamic linking, and it will not be executable on alpine.

(see mattn/go-sqlite3#384 (comment) for more information)

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Agreed, thanks for the explanation.


# build frontend
RUN git clone https://github.com/creationix/nvm.git /tmp/nvm
RUN /bin/bash -c "source /tmp/nvm/nvm.sh && nvm install node"
RUN /bin/bash -c "source /tmp/nvm/nvm.sh && npm install"
RUN /bin/bash -c "source /tmp/nvm/nvm.sh && npm run-script build"
RUN cp /go/src/commento/assets /go/bin/assets -vr

# set entrypoint
ENTRYPOINT /go/bin/commento
# Build frontend
FROM node:8.8-alpine as frontend-build

COPY ./package.json /commento/package.json
WORKDIR /commento/

RUN npm install

COPY ./assets/ /commento/assets/

RUN npm build


# Build final image
FROM alpine:3.6

COPY --from=backend-build /go/src/commento/commento /commento/
COPY --from=frontend-build /commento/assets/ /commento/assets/

RUN mkdir /commento-data/
ENV COMMENTO_DATABASE_FILE /commento-data/sqlite3.db

ENTRYPOINT /commento/commento
7 changes: 4 additions & 3 deletions config.go
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@@ -1,15 +1,16 @@
package main

import (
"strings"
"os"
"github.com/joho/godotenv"
"os"
"strings"
)

func loadConfig() error {
// Default value for each environment variable.
env := map[string]string{
"COMMENTO_PORT": "8080",
"COMMENTO_DATABASE_FILE": "sqlite3.db",
"COMMENTO_PORT": "8080",
}

// Load configuration from the environment. Final value is governed by the
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6 changes: 3 additions & 3 deletions main.go
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Expand Up @@ -11,12 +11,13 @@ import (
func main() {
var err error

err = LoadDatabase("sqlite:file=sqlite3.db")
err = loadConfig()
if err != nil {
Die(err)
}

err = loadConfig()
fp := os.Getenv("COMMENTO_DATABASE_FILE")
err = LoadDatabase("sqlite:file=" + fp)
if err != nil {
Die(err)
}
Expand All @@ -29,7 +30,6 @@ func main() {
http.HandleFunc("/get", GetCommentsHandler)

port := os.Getenv("COMMENTO_PORT")

svr := &http.Server{
Addr: ":" + port,
ReadTimeout: 5 * time.Second,
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