Caching 下载资源时,有哪些策略使Dockerfile指令缓存无效
我们的一些Docker映像需要从Nexus服务器或互联网下载更大的二进制文件,后者负责分发Java、Node.js、移动(Android和iOS)应用程序。例如,使用ADD或RUN指令下载Caching 下载资源时,有哪些策略使Dockerfile指令缓存无效,caching,build,docker,dockerfile,Caching,Build,Docker,Dockerfile,我们的一些Docker映像需要从Nexus服务器或互联网下载更大的二进制文件,后者负责分发Java、Node.js、移动(Android和iOS)应用程序。例如,使用ADD或RUN指令下载 RUN curl -o docker https://get.docker.com/builds/Linux/x86_64/docker-latest 考虑到“docker build”命令将根据文件的mtime查看指令和缓存,那么在构建这些映像时利用缓存机制避免重新下载整个二进制文件的方法是什么 另一个问
RUN curl -o docker https://get.docker.com/builds/Linux/x86_64/docker-latest
考虑到“docker build”命令将根据文件的mtime查看指令和缓存,那么在构建这些映像时利用缓存机制避免重新下载整个二进制文件的方法是什么
另一个问题是,如果资源发生更改,Docker将不会下载最新版本。解决方案
Docker在使用“RUN curl”或ADD下载之前不会查看任何缓存机制。它将重复下载步骤。但是,如果文件的mtime发生了更改,Docker会使缓存失效
在从文件存储或存储库(如Nexus、Amazon S3)构建具有依赖关系的DockerFile时,我一直致力于解决这个问题的一个策略是从资源中检索ETag,缓存它,并修改缓存标志文件的mdtime。(). 它遵循Python()、Node.js()项目中执行的方法
以下是我们可以做的:
- Docker将检查文件的mtime元数据,以确定是否使缓存无效
- 如果先前的指令无效,Docker将重新下载该文件。否则,将使用缓存
- 这模拟了文件的Nexus或S3存储
- 缓存ETag的当前值
- 此外,如果文件已更改,则保留更改。在这方面,是的
- 重新生成映像并验证从属层是否将无效,从而触发下载李>
// You'll see the client-side's output on the console when you run it.
var restify = require('restify');
// Server
var server = restify.createServer({
name: 'myapp',
version: '1.0.0'
});
server.head("/", function (req, res, next) {
res.writeHead(200, {'Content-Type': 'application/json; charset=utf-8',
'ETag': '"{SHA1{465fb0d9b9f143ad691c7c3bcf3801b47284f8555}}"'});
res.end();
return next();
});
server.get("/", function (req, res, next) {
res.writeHead(200, {'Content-Type': 'application/json; charset=utf-8',
'ETag': '"{SHA1{465fb0d9b9f143ad691c7c3bcf3801b47284f8555}}"'});
res.write("The file to be downloaded");
res.end();
return next();
});
server.listen(80, function () {
console.log('%s listening at %s', server.name, server.url);
});
// Client
var client = restify.createJsonClient({
url: 'http://localhost:80',
version: '~1.0'
});
client.head('/', function (err, req, res, obj) {
if(err) console.log("An error ocurred:", err);
else console.log('HEAD / returned headers: %j', res.headers);
});
执行此操作将为您提供:
mdesales@ubuntu [11/27/201411:10:49] ~/dev/icode/fuego/interview (feature/supportLogAuditor *) $ node testserver.js
myapp listening at http://0.0.0.0:8181
HEAD / returned headers: {"content-type":"application/json; charset=utf-8",
"etag":"\"{SHA1{465fb0d9b9f143ad691c7c3bcf3801b47284f8555}}\"",
"date":"Thu, 27 Nov 2014 19:10:50 GMT","connection":"keep-alive"}
2.基于ETag值构建图像
考虑以下在文件中缓存ETag头的构建脚本
#!/bin/sh
# Delete the existing first, and get the headers of the server to a file "headers.txt"
# Grep the ETag to a "new-docker.etag" file
# If the file exists, verify if the ETag has changed and/or move/modify the mtime of the file
# Proceed with the "docker build" as usual
rm -f new-docker.etag
curl -I -D headers.txt http://192.168.248.133:8181/ && \
grep -o 'ETag[^*]*' headers.txt > new-docker.etag && \
rm -f headers.txt
if [ ! -f docker.etag ]; then
cp new-docker.etag docker.etag
else
new=$(cat docker.etag)
old=$(cat new-docker.etag)
echo "Old ETag = $old"
echo "New ETag = $new"
if [ "$old" != "$new" ]; then
mv new-docker.etag docker.etag
touch -t 200001010000.00 docker.etag
fi
fi
docker build -t platform.registry.docker.corp.intuit.net/container/mule:3.4.1 .
3.重建和使用缓存
考虑到我使用的是当前缓存,构建该缓存的结果如下
mdesales@ubuntu [11/27/201411:54:08] ~/dev/github-intuit/docker-images/platform/mule-3.4 (master) $ ./build.sh
HTTP/1.1 200 OK
Content-Type: application/json; charset=utf-8
ETag: "{SHA1{465fb0d9b9f143ad691c7c3bcf3801b47284f8555}}"
Date: Thu, 27 Nov 2014 19:54:16 GMT
Connection: keep-alive
Old ETag = ETag: "{SHA1{465fb0d9b9f143ad691c7c3bcf3801b47284f8555}}"
New ETag = ETag: "{SHA1{465fb0d9b9f143ad691c7c3bcf3801b47284f8555}}"
Sending build context to Docker daemon 51.71 kB
Sending build context to Docker daemon
Step 0 : FROM core.registry.docker.corp.intuit.net/runtime/java:7
---> 3eb1591273f5
Step 1 : MAINTAINER Marcello_deSales@intuit.com
---> Using cache
---> 9bb8fff83697
Step 2 : WORKDIR /opt
---> Using cache
---> 3e3c96d96fc9
Step 3 : ADD docker.etag /tmp/docker.etag
---> Using cache
---> db3f82289475
Step 4 : RUN cat /tmp/docker.etag
---> Using cache
---> 0d4147a5f5ee
Step 5 : RUN curl -o docker https://get.docker.com/builds/Linux/x86_64/docker-latest
---> Using cache
---> 6bd6e75be322
Successfully built 6bd6e75be322
4.模拟ETag变化
更改服务器上ETag的值并重新启动服务器以模拟新的更新将导致更新缓存标志文件并使缓存无效。例如,Etag更改为“465fb0d9b9f143ad691c7c3bcf3801b47284f8333”。重建将触发新下载,因为ETag文件已更新,Docker将在“添加”指令期间验证。在这里,第5步将再次运行
mdesales@ubuntu [11/27/201411:54:16] ~/dev/github-intuit/docker-images/platform/mule-3.4 (master) $ ./build.sh
HTTP/1.1 200 OK
Content-Type: application/json; charset=utf-8
ETag: "{SHA1{465fb0d9b9f143ad691c7c3bcf3801b47284f8333}}"
Date: Thu, 27 Nov 2014 19:54:45 GMT
Connection: keep-alive
Old ETag = ETag: "{SHA1{465fb0d9b9f143ad691c7c3bcf3801b47284f8333}}"
New ETag = ETag: "{SHA1{465fb0d9b9f143ad691c7c3bcf3801b47284f8555}}"
Sending build context to Docker daemon 50.69 kB
Sending build context to Docker daemon
Step 0 : FROM core.registry.docker.corp.intuit.net/runtime/java:7
---> 3eb1591273f5
Step 1 : MAINTAINER Marcello_deSales@intuit.com
---> Using cache
---> 9bb8fff83697
Step 2 : WORKDIR /opt
---> Using cache
---> 3e3c96d96fc9
Step 3 : ADD docker.etag /tmp/docker.etag
---> ac3b200c8cdc
Removing intermediate container 4cf0040dbc43
Step 4 : RUN cat /tmp/docker.etag
---> Running in 4dd38d30549a
ETag: "{SHA1{465fb0d9b9f143ad691c7c3bcf3801b47284f8333}}"
---> 4fafbeac2180
Removing intermediate container 4dd38d30549a
Step 5 : RUN curl -o docker https://get.docker.com/builds/Linux/x86_64/docker-latest
---> Running in de920c7a2e28
% Total % Received % Xferd Average Speed Time Time Time Current
Dload Upload Total Spent Left Speed
100 13.5M 100 13.5M 0 0 1361k 0 0:00:10 0:00:10 --:--:-- 2283k
---> 95aff324da85
Removing intermediate container de920c7a2e28
Successfully built 95aff324da85
5.再次重用缓存
考虑到ETag没有改变,缓存标志文件将继续保持不变,Docker将使用缓存进行超快速构建
mdesales@ubuntu [11/27/201411:54:56] ~/dev/github-intuit/docker-images/platform/mule-3.4 (master) $ ./build.sh
HTTP/1.1 200 OK
Content-Type: application/json; charset=utf-8
ETag: "{SHA1{465fb0d9b9f143ad691c7c3bcf3801b47284f8333}}"
Date: Thu, 27 Nov 2014 19:54:58 GMT
Connection: keep-alive
Old ETag = ETag: "{SHA1{465fb0d9b9f143ad691c7c3bcf3801b47284f8333}}"
New ETag = ETag: "{SHA1{465fb0d9b9f143ad691c7c3bcf3801b47284f8333}}"
Sending build context to Docker daemon 51.71 kB
Sending build context to Docker daemon
Step 0 : FROM core.registry.docker.corp.intuit.net/runtime/java:7
---> 3eb1591273f5
Step 1 : MAINTAINER Marcello_deSales@intuit.com
---> Using cache
---> 9bb8fff83697
Step 2 : WORKDIR /opt
---> Using cache
---> 3e3c96d96fc9
Step 3 : ADD docker.etag /tmp/docker.etag
---> Using cache
---> ac3b200c8cdc
Step 4 : RUN cat /tmp/docker.etag
---> Using cache
---> 4fafbeac2180
Step 5 : RUN curl -o docker https://get.docker.com/builds/Linux/x86_64/docker-latest
---> Using cache
---> 95aff324da85
Successfully built 95aff324da85
此策略已用于构建Node.js、Java和其他应用程序服务器或预构建的依赖项。我使用类似但更简单的方法: 假设我想添加一个名为
mybin
的二进制文件,可以从以下位置下载:
我在詹金斯的工作中做了以下几点
wget -N http://www.example.com/pub/mybin
在我的Docker文件中,我有:
COPY mybin /usr/local/bin/
只有当二进制文件在服务器上发生更改时,选项-N
才会下载二进制文件。第二次运行wget
作业时,我得到:
...
Length: 12262118 (12M) [application/octet-stream]
Server file no newer than local file ‘mybin’ -- not retrieving.
docker build使用缓存
mdesales@ubuntu [11/27/201411:54:56] ~/dev/github-intuit/docker-images/platform/mule-3.4 (master) $ ./build.sh
HTTP/1.1 200 OK
Content-Type: application/json; charset=utf-8
ETag: "{SHA1{465fb0d9b9f143ad691c7c3bcf3801b47284f8333}}"
Date: Thu, 27 Nov 2014 19:54:58 GMT
Connection: keep-alive
Old ETag = ETag: "{SHA1{465fb0d9b9f143ad691c7c3bcf3801b47284f8333}}"
New ETag = ETag: "{SHA1{465fb0d9b9f143ad691c7c3bcf3801b47284f8333}}"
Sending build context to Docker daemon 51.71 kB
Sending build context to Docker daemon
Step 0 : FROM core.registry.docker.corp.intuit.net/runtime/java:7
---> 3eb1591273f5
Step 1 : MAINTAINER Marcello_deSales@intuit.com
---> Using cache
---> 9bb8fff83697
Step 2 : WORKDIR /opt
---> Using cache
---> 3e3c96d96fc9
Step 3 : ADD docker.etag /tmp/docker.etag
---> Using cache
---> ac3b200c8cdc
Step 4 : RUN cat /tmp/docker.etag
---> Using cache
---> 4fafbeac2180
Step 5 : RUN curl -o docker https://get.docker.com/builds/Linux/x86_64/docker-latest
---> Using cache
---> 95aff324da85
Successfully built 95aff324da85
如果服务器上的二进制文件发生更改(当时间戳更改时),
wget
将再次下载二进制文件,从而使复制命令的缓存无效。没有看到此选项!谢谢