Quickly patch a docker image

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Revision as of 17:55, 13 September 2022 by Antony (talk | contribs) (fix C&P parts from first run :))
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Overview

In this example we are going to apply a 2 line patch to the xena nova_compute to fix vgpu. We will then update the image in our registry and push it.

I have tested this by copying out the original file that needs patching on a live system to a backup file, making the new version in a new file testing and then making a patch.

After this we will move on to making a new image using a Dockerfile and then pushing back to the registry

Make the patch on the live system

copy original and make new version with changes 

docker cp nova_compute:/var/lib/kolla/venv/lib/python3.6/site-packages/nova/virt/libvirt/config.py config.py.old
cp config.py.old config.py
vi config.py

ok now we creating a patch file like this using diff like this: 

diff -Naur config.py.old config.py > vgpu.patch
cat vgpu.patch
--- config.py.old       2022-06-08 18:06:30.000000000 +0200
+++ config.py   2022-06-10 17:01:49.000000000 +0200
@@ -3136,6 +3136,8 @@
         for c in xmldoc:
             if c.tag == "name":
                 self.name = c.text
+                if len(self.name) > 41:
+                    self.name = self.name[:41]
             elif c.tag == "parent":
                 self.parent = c.text
             elif c.tag == "capability" and c.get("type") in ['pci', 'net']:

ok great I will copy and past this file into my image building VM which is called centos stream 8 build in the admin project on the BMC demo system. if this has not changed then you should be able to hit this using

ssh centos@10.10.12.93

if you are on the VPN

patching the image on the centos-stream build vm

I have already setup this node to push to the registry

I make a patch folder in /home/centos/kolla-xena/nova-compute-vgpu-patch

I copy my patch file in (C&P in vi or scp is fine)

I make my script 

cat patch.sh
#!/bin/bash
if  [ ! -f ./config.py ]; then
  container_id=$(docker create registry.define-technology.com:5000/kolla/centos-source-nova-compute:13.1.0)
  docker cp $container_id:/var/lib/kolla/venv/lib/python3.6/site-packages/nova/virt/libvirt/config.py ./config.py
  patch --verbose --backup -p0 --forward ./config.py  vgpu.patch
  docker rm $container_id
fi
docker build ./ -t kolla/centos-source-nova-compute:13.1.0-vpgu

What this does is (if there is no config.py in pwd)

  1. create a temporary container from the unpatched version in the registry created using kolla-build (registry.define-technology.com:5000/kolla/centos-source-nova-compute:13.1.0)
  2. copy out the original file we want to modify and patch it here
  3. patch the file using our patch file we copy and pasted in (yes we could have copied the original instead and skipped all these steps but it's a pain to go from vpn to another vpn)
  4. remove out temporary container
  5. finally use a docker file in the current dir that we will create next and tag the image in the local machine as kolla/centos-source-nova-compute:13.1.0-vpgu

I make my Dockerfile 

cat Dockerfile
FROM registry.define-technology.com:5000/kolla/centos-source-nova-compute:13.1.0
MAINTAINER definetech
ADD config.py /var/lib/kolla/venv/lib/python3.6/site-packages/nova/virt/libvirt/config.py

What this does is pull the container from thee registry and add the file the script will make

I then make the patch script executable and run it 

chmod a+x patch.sh
./patch.sh 
[centos@centos-stream-8-build nova-compute-vgpu-patch]$ ./patch.sh
Hmm...  Looks like a unified diff to me...
The text leading up to this was:
--------------------------
|--- config.py.orig     2022-06-08 16:06:30.000000000 +0000
|+++ config.py  2022-09-13 15:12:33.000000000 +0000
--------------------------
patching file ./config.py.orig
Using Plan A...
Hunk #1 succeeded at 3136.
done
63e907d461e379f5aac0e01fd2e7a06ed192cc22dd7749000d15749f56af8a1d
Sending build context to Docker daemon    129kB
Step 1/3 : FROM registry.define-technology.com:5000/kolla/centos-source-nova-compute:13.1.0
 ---> d679222ce5f6
Step 2/3 : MAINTAINER definetech
 ---> Using cache
 ---> a5116a321cf4
Step 3/3 : ADD config.py /var/lib/kolla/venv/lib/python3.6/site-packages/nova/virt/libvirt/config.py
 ---> Using cache
 ---> 9f24ce46cb50
Successfully built 9f24ce46cb50
Successfully tagged kolla/centos-source-nova-compute:13.1.0-vpgu

OK cool!

retag the image and push it

we need to tag it into the remote registry and push it like this: I tag it 2x so the xena tag points to this latest one so my kolla-ansible deploy will auto pull it next time the other is a specific version I can grab easily 

docker image tag 6a73782c28e5 registry.define-technology.com:5000/kolla/centos-source-nova-compute:xena
docker image tag 6a73782c28e5 registry.define-technology.com:5000/kolla/centos-source-nova-compute:13.1.0-vpgu

I then push both 

 
[centos@centos-stream-8-build nov-compute-vgpu-patch]$ docker image push registry.define-technology.com:5000/kolla/centos-source-nova-compute:xena
The push refers to repository [registry.define-technology.com:5000/kolla/centos-source-nova-compute]
9edd2979f9d7: Pushed
10a928327833: Layer already exists
72e10fe91e4b: Layer already exists
1a955b80310b: Layer already exists
c1a9650e0fbe: Layer already exists
db13f4375cdb: Layer already exists
c86c5a7f9ba5: Layer already exists
0f03ed29d7ae: Layer already exists
157f8647b5a6: Layer already exists
c00b5c2f7e2b: Layer already exists
8a81428241a4: Layer already exists
5df710584acd: Layer already exists
e6c7a4598f0e: Layer already exists
ca327191c31a: Layer already exists
4d67bdd24bbe: Layer already exists
a4c469747181: Layer already exists
a87ed12b9bd5: Layer already exists
fa47a7b3f947: Layer already exists
db26ae996658: Layer already exists
f47b56de3bb8: Layer already exists
c15e6d575719: Layer already exists
3a23548130c2: Layer already exists
caa9beadec0d: Layer already exists
4f0c7c3cdca0: Layer already exists
e45fcf539a8f: Layer already exists
940953f5da7b: Layer already exists
2295777f2289: Layer already exists
0f9e2cd6f428: Layer already exists
d8ddf38fea32: Layer already exists
7e803b580653: Layer already exists
7f8db04cdf74: Layer already exists
b0d8b48a0361: Layer already exists
f1169f782306: Layer already exists
d7db75e2b431: Layer already exists
4f2cfc8e1d9c: Layer already exists
2fda120dca9d: Layer already exists
b20f86037b6a: Layer already exists
cfb384290b61: Layer already exists
2fa7a397a825: Layer already exists
7cec48be98b5: Layer already exists
e9f8533305d1: Layer already exists
f0e656ec34e5: Layer already exists
8fb83a9e4695: Layer already exists
6ffceb8347ee: Layer already exists
22a079a22b0a: Layer already exists
b8e0cedff7ca: Layer already exists
2beade966b29: Layer already exists
2bee813718b1: Layer already exists
de74aa5c66af: Layer already exists
0067d70a5699: Layer already exists
55746cb9d6dc: Layer already exists
5d9ef8a0564d: Layer already exists
e9b312bba1ab: Layer already exists
c86122b5e4d3: Layer already exists
3813924f3fa4: Layer already exists
xena: digest: sha256:cdbcd75ad9c9e551df481a33a5b4bcd273d0c6d48ebc36c24c49624d202822ce size: 11802
[centos@centos-stream-8-build nov-compute-vgpu-patch]$ docker image push registry.define-technology.com:5000/kolla/centos-source-nova-compute:13.1.0-vpgu
The push refers to repository [registry.define-technology.com:5000/kolla/centos-source-nova-compute]
9edd2979f9d7: Layer already exists
10a928327833: Layer already exists
72e10fe91e4b: Layer already exists
1a955b80310b: Layer already exists
c1a9650e0fbe: Layer already exists
db13f4375cdb: Layer already exists
c86c5a7f9ba5: Layer already exists
0f03ed29d7ae: Layer already exists
157f8647b5a6: Layer already exists
c00b5c2f7e2b: Layer already exists
8a81428241a4: Layer already exists
5df710584acd: Layer already exists
e6c7a4598f0e: Layer already exists
ca327191c31a: Layer already exists
4d67bdd24bbe: Layer already exists
a4c469747181: Layer already exists
a87ed12b9bd5: Layer already exists
fa47a7b3f947: Layer already exists
db26ae996658: Layer already exists
f47b56de3bb8: Layer already exists
c15e6d575719: Layer already exists
3a23548130c2: Layer already exists
caa9beadec0d: Layer already exists
4f0c7c3cdca0: Layer already exists
e45fcf539a8f: Layer already exists
940953f5da7b: Layer already exists
2295777f2289: Layer already exists
0f9e2cd6f428: Layer already exists
d8ddf38fea32: Layer already exists
7e803b580653: Layer already exists
7f8db04cdf74: Layer already exists
b0d8b48a0361: Layer already exists
f1169f782306: Layer already exists
d7db75e2b431: Layer already exists
4f2cfc8e1d9c: Layer already exists
2fda120dca9d: Layer already exists
b20f86037b6a: Layer already exists
cfb384290b61: Layer already exists
2fa7a397a825: Layer already exists
7cec48be98b5: Layer already exists
e9f8533305d1: Layer already exists
f0e656ec34e5: Layer already exists
8fb83a9e4695: Layer already exists
6ffceb8347ee: Layer already exists
22a079a22b0a: Layer already exists
b8e0cedff7ca: Layer already exists
2beade966b29: Layer already exists
2bee813718b1: Layer already exists
de74aa5c66af: Layer already exists
0067d70a5699: Layer already exists
55746cb9d6dc: Layer already exists
5d9ef8a0564d: Layer already exists
e9b312bba1ab: Layer already exists
c86122b5e4d3: Layer already exists
3813924f3fa4: Layer already exists
13.1.0-vpgu: digest: sha256:cdbcd75ad9c9e551df481a33a5b4bcd273d0c6d48ebc36c24c49624d202822ce size: 11802

Done!

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