Clever Geek Handbook

DĂ©ploiement bleu-vert au salaire minimum

Dans cet article, nous utilisons bash , ssh , docker et nginx pour organiser une mise en page transparente d'une application Web. Le dĂ©ploiement bleu-vert est une technique qui vous permet de mettre Ă  jour instantanĂ©ment votre application sans rejeter aucune demande. Il s'agit de l'une des stratĂ©gies de dĂ©ploiement sans temps d'arrĂȘt et convient le mieux aux applications qui ont une instance, mais il est possible de charger une deuxiĂšme instance prĂȘte Ă  fonctionner cĂŽte Ă  cĂŽte.



Supposons que vous ayez une application Web avec laquelle de nombreux clients travaillent activement et qu'elle ne peut absolument pas s'allonger pendant quelques secondes. Et vous devez vraiment dĂ©ployer une mise Ă  jour de la bibliothĂšque, corriger un bogue ou une nouvelle fonctionnalitĂ© intĂ©ressante. Dans une situation normale, vous devrez arrĂȘter l'application, la remplacer et la redĂ©marrer. Dans le cas de docker, vous pouvez d'abord remplacer, puis redĂ©marrer, mais il y aura toujours une pĂ©riode pendant laquelle les demandes adressĂ©es Ă  l'application ne seront pas traitĂ©es, car l'application prend gĂ©nĂ©ralement un certain temps pour dĂ©marrer. Que faire s'il dĂ©marre, mais s'avĂšre inopĂ©rant? C'est la tĂąche, rĂ©solvons-la avec des moyens minimaux et aussi Ă©lĂ©gants que possible.



Avertissement: La plupart de l'article est présenté dans un format expérimental - sous la forme d'un enregistrement de session console. Espérons que ce ne sera pas trÚs difficile à comprendre, et ce code se documente un peu. Pour l'ambiance, imaginez que ce ne sont pas que des extraits de code, mais du papier provenant d'un télétype «de fer».





Des techniques intéressantes qui sont difficiles pour Google simplement en lisant le code sont décrites au début de chaque section. Si vous ne comprenez pas autre chose - google et enregistrez-vous expliquehell (heureusement, cela fonctionne à nouveau, en raison du déblocage du télégramme). Ce qui n'est pas googlé - demandez dans les commentaires. Je suis heureux d'ajouter la section appropriée «Techniques intéressantes».



Commençons.



$ mkdir blue-green-deployment && cd $_


Un service



Créons un service expérimental et placez-le dans un conteneur.



Techniques intéressantes







, Python. . , ( ), .


$ cat << EOF > uptimer.py


from http.server import BaseHTTPRequestHandler, HTTPServer
from time import monotonic

app_version = 1
app_name = f'Uptimer v{app_version}.0'
loading_seconds = 15 - app_version * 5

class Handler(BaseHTTPRequestHandler):
    def do_GET(self):
        if self.path == '/':
            try:
                t = monotonic() - server_start
                if t < loading_seconds:
                    self.send_error(503)
                else:
                    self.send_response(200)
                    self.send_header('Content-Type', 'text/html')
                    self.end_headers()
                    response = f'<h2>{app_name} is running for {t:3.1f} seconds.</h2>\n'
                    self.wfile.write(response.encode('utf-8'))
            except Exception:
                self.send_error(500)
        else:
            self.send_error(404)

httpd = HTTPServer(('', 8080), Handler)
server_start = monotonic()
print(f'{app_name} (loads in {loading_seconds} sec.) started.')
httpd.serve_forever()


EOF

$ cat << EOF > Dockerfile
FROM python:alpine
EXPOSE 8080
COPY uptimer.py app.py
CMD [ "python", "-u", "./app.py" ]
EOF

$ docker build --tag uptimer .
Sending build context to Docker daemon  39.42kB
Step 1/4 : FROM python:alpine
 ---> 8ecf5a48c789
Step 2/4 : EXPOSE 8080
 ---> Using cache
 ---> cf92d174c9d3
Step 3/4 : COPY uptimer.py app.py
 ---> a7fbb33d6b7e
Step 4/4 : CMD [ "python", "-u", "./app.py" ]
 ---> Running in 1906b4bd9fdf
Removing intermediate container 1906b4bd9fdf
 ---> c1655b996fe8
Successfully built c1655b996fe8
Successfully tagged uptimer:latest

$ docker run --rm --detach --name uptimer --publish 8080:8080 uptimer
8f88c944b8bf78974a5727070a94c76aa0b9bb2b3ecf6324b784e782614b2fbf

$ docker ps
CONTAINER ID        IMAGE               COMMAND                CREATED             STATUS              PORTS                    NAMES
8f88c944b8bf        uptimer             "python -u ./app.py"   3 seconds ago       Up 5 seconds        0.0.0.0:8080->8080/tcp   uptimer

$ docker logs uptimer
Uptimer v1.0 (loads in 10 sec.) started.

$ wget -qSO- http://localhost:8080
  HTTP/1.0 503 Service Unavailable
  Server: BaseHTTP/0.6 Python/3.8.3
  Date: Sat, 22 Aug 2020 19:52:40 GMT
  Connection: close
  Content-Type: text/html;charset=utf-8
  Content-Length: 484

$ wget -qSO- http://localhost:8080
  HTTP/1.0 200 OK
  Server: BaseHTTP/0.6 Python/3.8.3
  Date: Sat, 22 Aug 2020 19:52:45 GMT
  Content-Type: text/html
<h2>Uptimer v1.0 is running for 15.4 seconds.</h2>

$ docker rm --force uptimer
uptimer


-



, , - , . - nginx -. - . .



- docker network. , -, .



- , docker network - , --publish, -.



- 80, , . 80- , --publish 80:80 --publish ANY_FREE_PORT:80.









$ docker network create web-gateway
5dba128fb3b255b02ac012ded1906b7b4970b728fb7db3dbbeccc9a77a5dd7bd

$ docker run --detach --rm --name uptimer --network web-gateway uptimer
a1105f1b583dead9415e99864718cc807cc1db1c763870f40ea38bc026e2d67f

$ docker run --rm --network web-gateway alpine wget -qO- http://uptimer:8080
<h2>Uptimer v1.0 is running for 11.5 seconds.</h2>

$ docker run --detach --publish 80:80 --network web-gateway --name reverse-proxy nginx:alpine
80695a822c19051260c66bf60605dcb4ea66802c754037704968bc42527bf120

$ docker ps
CONTAINER ID        IMAGE               COMMAND                  CREATED              STATUS              PORTS                NAMES
80695a822c19        nginx:alpine        "/docker-entrypoint.
"   27 seconds ago       Up 25 seconds       0.0.0.0:80->80/tcp   reverse-proxy
a1105f1b583d        uptimer             "python -u ./app.py"     About a minute ago   Up About a minute   8080/tcp             uptimer

$ cat << EOF > uptimer.conf
server {
    listen 80;
    location / {
        proxy_pass http://uptimer:8080;
    }
}
EOF

$ docker cp ./uptimer.conf reverse-proxy:/etc/nginx/conf.d/default.conf

$ docker exec reverse-proxy nginx -s reload
2020/06/23 20:51:03 [notice] 31#31: signal process started

$ wget -qSO- http://localhost
  HTTP/1.1 200 OK
  Server: nginx/1.19.0
  Date: Sat, 22 Aug 2020 19:56:24 GMT
  Content-Type: text/html
  Transfer-Encoding: chunked
  Connection: keep-alive
<h2>Uptimer v1.0 is running for 104.1 seconds.</h2>




( startup performance) .





  • echo 'my text' | docker exec -i my-container sh -c 'cat > /my-file.txt' — my text /my-file.txt my-container.
  • cat > /my-file.txt — /dev/stdin.




$ sed -i "s/app_version = 1/app_version = 2/" uptimer.py

$ docker build --tag uptimer .
Sending build context to Docker daemon  39.94kB
Step 1/4 : FROM python:alpine
 ---> 8ecf5a48c789
Step 2/4 : EXPOSE 8080
 ---> Using cache
 ---> cf92d174c9d3
Step 3/4 : COPY uptimer.py app.py
 ---> 3eca6a51cb2d
Step 4/4 : CMD [ "python", "-u", "./app.py" ]
 ---> Running in 8f13c6d3d9e7
Removing intermediate container 8f13c6d3d9e7
 ---> 1d56897841ec
Successfully built 1d56897841ec
Successfully tagged uptimer:latest

$ docker run --detach --rm --name uptimer_BLUE --network web-gateway uptimer
96932d4ca97a25b1b42d1b5f0ede993b43f95fac3c064262c5c527e16c119e02

$ docker logs uptimer_BLUE
Uptimer v2.0 (loads in 5 sec.) started.

$ docker run --rm --network web-gateway alpine wget -qO- http://uptimer_BLUE:8080
<h2>Uptimer v2.0 is running for 23.9 seconds.</h2>

$ sed s/uptimer/uptimer_BLUE/ uptimer.conf | docker exec --interactive reverse-proxy sh -c 'cat > /etc/nginx/conf.d/default.conf'

$ docker exec reverse-proxy cat /etc/nginx/conf.d/default.conf
server {
    listen 80;
    location / {
        proxy_pass http://uptimer_BLUE:8080;
    }
}

$ docker exec reverse-proxy nginx -s reload
2020/06/25 21:22:23 [notice] 68#68: signal process started

$ wget -qO- http://localhost
<h2>Uptimer v2.0 is running for 63.4 seconds.</h2>

$ docker rm -f uptimer
uptimer

$ wget -qO- http://localhost
<h2>Uptimer v2.0 is running for 84.8 seconds.</h2>

$ docker ps
CONTAINER ID        IMAGE               COMMAND                  CREATED              STATUS              PORTS                NAMES
96932d4ca97a        uptimer             "python -u ./app.py"     About a minute ago   Up About a minute   8080/tcp             uptimer_BLUE
80695a822c19        nginx:alpine        "/docker-entrypoint.
"   8 minutes ago        Up 8 minutes        0.0.0.0:80->80/tcp   reverse-proxy


, , . (, CI-) .





, localhost localhost , . :



$ ssh production-server docker image ls
REPOSITORY          TAG                 IMAGE ID            CREATED             SIZE

$ docker image save uptimer | ssh production-server 'docker image load'
Loaded image: uptimer:latest

$ ssh production-server docker image ls
REPOSITORY          TAG                 IMAGE ID            CREATED             SIZE
uptimer             latest              1d56897841ec        5 minutes ago       78.9MB


docker save .tar , 1.5 , . :



$ docker image save uptimer | gzip | ssh production-server 'zcat | docker image load'
Loaded image: uptimer:latest


, (, ):



$ docker image save uptimer | gzip | pv | ssh production-server 'zcat | docker image load'
25,7MiB 0:01:01 [ 425KiB/s] [                   <=>    ]
Loaded image: uptimer:latest


: SSH , ~/.ssh/config.

docker image save/load — , . :



  1. Container Registry ( ).
  2. docker daemon :

    1. DOCKER_HOST.
    2. -H --host docker-compose.
    3. docker context


( ) How to deploy on remote Docker hosts with docker-compose.



deploy.sh



, . top-level , , .





  • ${parameter?err_msg} — bash- (aka parameter substitution). parameter , err_msg 1.
  • docker --log-driver journald — -, - . , production- .




deploy() {
    local image_name=${1?"Usage: ${FUNCNAME[0]} image_name"}

    ensure-reverse-proxy || return 2
    if get-active-slot $image_name
    then
        local OLD=${image_name}_BLUE
        local new_slot=GREEN
    else
        local OLD=${image_name}_GREEN
        local new_slot=BLUE
    fi
    local NEW=${image_name}_${new_slot}
    echo "Deploying '$NEW' in place of '$OLD'..."
    docker run \
        --detach \
        --restart always \
        --log-driver journald \
        --name $NEW \
        --network web-gateway \
        $image_name || return 3
    echo "Container started. Checking health..."
    for i in {1..20}
    do
        sleep 1
        if get-service-status $image_name $new_slot
        then
            echo "New '$NEW' service seems OK. Switching heads..."
            sleep 2  # Ensure service is ready
            set-active-slot $image_name $new_slot || return 4
            echo "The '$NEW' service is live!"
            sleep 2  # Ensure all requests were processed
            echo "Killing '$OLD'..."
            docker rm -f $OLD
            docker image prune -f
            echo "Deployment successful!"
            return 0
        fi
        echo "New '$NEW' service is not ready yet. Waiting ($i)..."
    done
    echo "New '$NEW' service did not raise, killing it. Failed to deploy T_T"
    docker rm -f $NEW
    return 5
}


:



  • ensure-reverse-proxy — , - ( )
  • get-active-slot service_name — (BLUE GREEN)
  • get-service-status service_name deployment_slot —
  • set-active-slot service_name deployment_slot — nginx -


:



ensure-reverse-proxy() {
    is-container-up reverse-proxy && return 0
    echo "Deploying reverse-proxy..."
    docker network create web-gateway
    docker run \
        --detach \
        --restart always \
        --log-driver journald \
        --name reverse-proxy \
        --network web-gateway \
        --publish 80:80 \
        nginx:alpine || return 1
    docker exec --interactive reverse-proxy sh -c "> /etc/nginx/conf.d/default.conf"
    docker exec reverse-proxy nginx -s reload
}

is-container-up() {
    local container=${1?"Usage: ${FUNCNAME[0]} container_name"}

    [ -n "$(docker ps -f name=${container} -q)" ]
    return $?
}

get-active-slot() {
    local image=${1?"Usage: ${FUNCNAME[0]} image_name"}

    if is-container-up ${image}_BLUE && is-container-up ${image}_GREEN; then
        echo "Collision detected! Stopping ${image}_GREEN..."
        docker rm -f ${image}_GREEN
        return 0  # BLUE
    fi
    if is-container-up ${image}_BLUE && ! is-container-up ${image}_GREEN; then
        return 0  # BLUE
    fi
    if ! is-container-up ${image}_BLUE; then
        return 1  # GREEN
    fi
}

get-service-status() {
    local usage_msg="Usage: ${FUNCNAME[0]} image_name deployment_slot"
    local image=${1?usage_msg}
    local slot=${2?$usage_msg}

    case $image in
        # Add specific healthcheck paths for your services here
        *) local health_check_port_path=":8080/" ;;
    esac
    local health_check_address="http://${image}_${slot}${health_check_port_path}"
    echo "Requesting '$health_check_address' within the 'web-gateway' docker network:"
    docker run --rm --network web-gateway alpine \
        wget --timeout=1 --quiet --server-response $health_check_address
    return $?
}

set-active-slot() {
    local usage_msg="Usage: ${FUNCNAME[0]} service_name deployment_slot"
    local service=${1?$usage_msg}
    local slot=${2?$usage_msg}
    [ "$slot" == BLUE ] || [ "$slot" == GREEN ] || return 1

    get-nginx-config $service $slot | docker exec --interactive reverse-proxy sh -c "cat > /etc/nginx/conf.d/$service.conf"
    docker exec reverse-proxy nginx -t || return 2
    docker exec reverse-proxy nginx -s reload
}


get-active-slot :



, ?

, exit code bash , . , :

get-active-slot service && echo BLUE || echo GREEN.



, ?



, , else.



, nginx: get-nginx-config service_name deployment_slot. , . — cat <<- EOF, . , — , . bash , nginx . , . , , " ", 4 EOF. .



, cat << 'EOF', . cat << EOF, heredoc ( ($foo), ($(bar)) ..), , $ . .


get-nginx-config() {
    local usage_msg="Usage: ${FUNCNAME[0]} image_name deployment_slot"
    local image=${1?$usage_msg}
    local slot=${2?$usage_msg}
    [ "$slot" == BLUE ] || [ "$slot" == GREEN ] || return 1

    local container_name=${image}_${slot}
    case $image in
        # Add specific nginx configs for your services here
        *) nginx-config-simple-service $container_name:8080 ;;
    esac
}

nginx-config-simple-service() {
    local usage_msg="Usage: ${FUNCNAME[0]} proxy_pass"
    local proxy_pass=${1?$usage_msg}

cat << EOF
server {
    listen 80;
    location / {
        proxy_pass http://$proxy_pass;
    }
}
EOF
}


. wget curl.





. localhost :



$ ssh-copy-id localhost
/usr/bin/ssh-copy-id: INFO: attempting to log in with the new key(s), to filter out any that are already installed
/usr/bin/ssh-copy-id: INFO: 1 key(s) remain to be installed -- if you are prompted now it is to install the new keys
himura@localhost's password: 

Number of key(s) added: 1

Now try logging into the machine, with:   "ssh 'localhost'"
and check to make sure that only the key(s) you wanted were added.


, , ? , - ( nginx url ). , ( ), , = .



1: , scp. ssh .



:



  • , , .
  • ( ).
  • .


2:



  • sed
  • shh pipe (|)


:



  • Truely stateless
  • No boilerplate entities
  • Feeling cool


Ansible. , . , . , , :



$ cat << 'EOF' > deploy.sh


#!/bin/bash

usage_msg="Usage: $0 ssh_address local_image_tag"
ssh_address=${1?$usage_msg}
image_name=${2?$usage_msg}

echo "Connecting to '$ssh_address' via ssh to seamlessly deploy '$image_name'..."
( sed "\$a deploy $image_name" | ssh -T $ssh_address ) << 'END_OF_SCRIPT'
deploy() {
    echo "Yay! The '${FUNCNAME[0]}' function is executing on '$(hostname)' with argument '$1'"
}
END_OF_SCRIPT


EOF

$ chmod +x deploy.sh

$ ./deploy.sh localhost magic-porridge-pot
Connecting to 'localhost' via ssh to seamlessly deploy 'magic-pot'...
Yay! The 'deploy' function is executing on 'hut' with argument 'magic-porridge-pot'


, , bash, ( shellbang):



if [ "$SHELL" != "/bin/bash" ]
then
    echo "The '$SHELL' shell is not supported by 'deploy.sh'. Set a '/bin/bash' shell for '$USER@$HOSTNAME'."
    exit 1
fi


-:



$ docker exec reverse-proxy rm /etc/nginx/conf.d/default.conf

$ wget -qO deploy.sh https://git.io/JUc2s

$ chmod +x deploy.sh

$ ./deploy.sh localhost uptimer
Sending gzipped image 'uptimer' to 'localhost' via ssh...
Loaded image: uptimer:latest
Connecting to 'localhost' via ssh to seamlessly deploy 'uptimer'...
Deploying 'uptimer_GREEN' in place of 'uptimer_BLUE'...
06f5bc70e9c4f930e7b1f826ae2ca2f536023cc01e82c2b97b2c84d68048b18a
Container started. Checking health...
Requesting 'http://uptimer_GREEN:8080/' within the 'web-gateway' docker network:
  HTTP/1.0 503 Service Unavailable
wget: server returned error: HTTP/1.0 503 Service Unavailable
New 'uptimer_GREEN' service is not ready yet. Waiting (1)...
Requesting 'http://uptimer_GREEN:8080/' within the 'web-gateway' docker network:
  HTTP/1.0 503 Service Unavailable
wget: server returned error: HTTP/1.0 503 Service Unavailable
New 'uptimer_GREEN' service is not ready yet. Waiting (2)...
Requesting 'http://uptimer_GREEN:8080/' within the 'web-gateway' docker network:
  HTTP/1.0 200 OK
  Server: BaseHTTP/0.6 Python/3.8.3
  Date: Sat, 22 Aug 2020 20:15:50 GMT
  Content-Type: text/html

New 'uptimer_GREEN' service seems OK. Switching heads...
nginx: the configuration file /etc/nginx/nginx.conf syntax is ok
nginx: configuration file /etc/nginx/nginx.conf test is successful
2020/08/22 20:15:54 [notice] 97#97: signal process started
The 'uptimer_GREEN' service is live!
Killing 'uptimer_BLUE'...
uptimer_BLUE
Total reclaimed space: 0B
Deployment successful!


http://localhost/ , , .



:3



$ docker rm -f uptimer_GREEN reverse-proxy 
uptimer_GREEN
reverse-proxy

$ docker network rm web-gateway 
web-gateway

$ cd ..

$ rm -r blue-green-deployment




Disclaimer: . , bash-. bash — , , , systemd, systemd /etc/init.d/ . , Docker Swarm Mode () et de nombreux orchestrateurs puissants avec des tonnes de mises en page homogĂšnes prĂȘtes Ă  l'emploi. Mais les instruments prĂȘts Ă  l'emploi ne sont jamais la panacĂ©e. Ce script est nĂ© non seulement par amour pour les scripts bash, mais aussi parce qu'il y a longtemps, dans une galaxie lointaine, trĂšs lointaine, il s'est avĂ©rĂ© plus facile Ă  Ă©crire qu'Ă  implĂ©menter un orchestrateur. De plus, il peut ĂȘtre facilement modifiĂ© pour rĂ©pondre aux besoins spĂ©cifiques d'applications spĂ©cifiques.



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