In this chapter, we will build an application’s Docker image using werf and Dockerfile. Then, we will test the built image by running it locally.
Preliminary steps
Install werf and its dependencies using this guide.
Create a new repository with the application
Run the following commands in PowerShell:
# Clone the example repository to ~/werf-guide/guides (if you have not cloned it yet).
if (-not (Test-Path ~/werf-guide/guides)) {
git clone https://github.com/werf/website $env:HOMEPATH/werf-guide/guides
}
# Copy the (unchanged) application files to ~/werf-guide/app.
rm -Recurse -Force ~/werf-guide/app
cp -Recurse -Force ~/werf-guide/guides/examples/basic/000_app ~/werf-guide/app
# Make the ~/werf-guide/app directory a git repository.
cd ~/werf-guide/app
git init
git add .
git commit -m initial
# To see what changes we will make later in this chapter, let's replace all the application files
# in the repository with new, modified files containing the changes described below.
git rm -r .
cp -Recurse -Force ~/werf-guide/guides/examples/basic/001_build/* .
git add .
git commit -m WIP
# Enter the command below to show the files we are going to change.
git show --stat
# Enter the command below to show the changes that will be made.
git show
Run the following commands in Bash:
# Clone the example repository to ~/werf-guide/guides (if you have not cloned it yet).
test -e ~/werf-guide/guides || git clone https://github.com/werf/website ~/werf-guide/guides
# Copy the (unchanged) application files to ~/werf-guide/app.
rm -rf ~/werf-guide/app
cp -rf ~/werf-guide/guides/examples/basic/000_app ~/werf-guide/app
# Make the ~/werf-guide/app directory a git repository.
cd ~/werf-guide/app
git init
git add .
git commit -m initial
# To see what changes we will make later in this chapter, let's replace all the application files
# in the repository with new, modified files containing the changes described below.
git rm -r .
cp -rf ~/werf-guide/guides/examples/basic/001_build/. .
git add .
git commit -m WIP
# Enter the command below to show files we are going to change.
git show --stat
# Enter the command below to show the changes that will be made.
git show
Dockerfile
In Windows, we recommend using Notepad++ or any other suitable editor instead of regular Notepad bundled with the OS.
Dockerfile contains all the steps required to build our application:
FROM alpine:3.14
WORKDIR /app
# Install app dependencies.
RUN apk add --no-cache --update nmap-ncat
# Add to the image a script to run the echo server and set the permission to execution.
COPY start.sh .
RUN chmod +x start.sh
Integrating werf with Dockerfile
The primary werf configuration file, werf.yaml (in the repository’s root) specifies Dockerfile to use when building an application with werf:
project: werf-guide-app
configVersion: 1
---
image: app
dockerfile: Dockerfile
The werf.yaml file can describe the assembly of multiple images at once. There are also some additional settings for building an image. You can learn more about them in the documentation.
Building using werf
Note that before starting the werf-based build/deploy process, you have to add all the files to the commit.
Below, we will discuss why this is necessary and how to avoid creating unnecessary commits during local development.
We already did this in the “Creating a new application repository” section above. Normally, however, you have to run the git add and git commit commands.
Start the build using the werf build command:
werf build
Here is the output if the build was successful:
┌ ⛵ image app
│ ┌ Building stage app/dockerfile
│ │ app/dockerfile Sending build context to Docker daemon 4.096kB
│ │ app/dockerfile Step 1/14 : FROM alpine:3.14
│ │ app/dockerfile ---> d4ff818577bc
│ │ app/dockerfile Step 2/14 : WORKDIR /app
│ │ app/dockerfile ---> Using cache
│ │ app/dockerfile ---> fecacd1a1c75
│ │ app/dockerfile Step 3/14 : RUN apk add --no-cache --update nmap-ncat
│ │ app/dockerfile ---> Running in 9bead7817a6d
│ │ app/dockerfile fetch https://dl-cdn.alpinelinux.org/alpine/v3.14/main/x86_64/APKINDEX.tar.gz
│ │ app/dockerfile fetch https://dl-cdn.alpinelinux.org/alpine/v3.14/community/x86_64/APKINDEX.tar.gz
│ │ app/dockerfile (1/3) Installing lua5.3-libs (5.3.6-r0)
│ │ app/dockerfile (2/3) Installing libpcap (1.10.0-r0)
│ │ app/dockerfile (3/3) Installing nmap-ncat (7.91-r0)
│ │ app/dockerfile Executing busybox-1.33.1-r2.trigger
│ │ app/dockerfile OK: 6 MiB in 17 packages
│ │ app/dockerfile Removing intermediate container 9bead7817a6d
│ │ app/dockerfile ---> ac1cbf858c89
│ │ app/dockerfile Step 4/14 : COPY start.sh .
│ │ app/dockerfile ---> 0f51cefb9aaf
│ │ app/dockerfile Step 5/14 : RUN chmod +x start.sh
│ │ app/dockerfile ---> Running in c87188cc85f7
│ │ app/dockerfile Removing intermediate container c87188cc85f7
│ │ app/dockerfile ---> 7d47843543ed
│ │ app/dockerfile ...
│ │ app/dockerfile Successfully built 3091b84c90c3
│ │ app/dockerfile Successfully tagged 10560bef-f182-4769-bb23-c4a465814016:latest
│ ├ Info
│ │ name: werf-guide-app:638307ec810d3921a7b4f96c775d8aa8826fb0b2e1ac81fc793f02a6-1625134265354
│ │ id: 4c3c2a9e934c
│ │ created: 2022-07-01 11:11:05.3235952 +0000 UTC
│ │ size: 6.0 MiB
│ └ Building stage app/dockerfile (9.98 seconds)
└ ⛵ image app (10.85 seconds)
Running time 11.02 seconds
Starting the application
You can run the container locally using the built image via the werf run command:
werf run app --docker-options="-ti --rm -p 8000:8000" -- /app/start.sh
Here, the --docker-options flag sets the Docker parameters, while the command to run in the container is given at the end (after two hyphens).
Go to http://127.0.0.1:8000/ping in the browser to check if the application is running. Alternatively, you can use the curl utility:
curl http://127.0.0.1:8000/ping
You will get the pong message in response, and the following text will appear in the container log:
GET /ping HTTP/1.1
Host: 127.0.0.1:8000
User-Agent: curl/7.67.0
Accept: */*
