File content not changed but COPY command invalidates cache! #10336
Description
How to reproduce:
- Create new Dockerfile using COPY command and commit to GIT repository
- Checkout GIT repository and run Docker build on machine A
- Push created images to private registry or export it
- Pull image from private registry or import on machine B
- Checkout the same commit from GIT repository and run Docker build on machine B
Result:
First run on machine A:
build 24-Jan-2015 22:58:16 Step 8 : RUN cd /usr/local/src/APC-3.1.13; /usr/local/bin/phpize; ./configure --with-php-config=/usr/local/bin/php-config; make; make install
build 24-Jan-2015 22:58:16 ---> Using cache
build 24-Jan-2015 22:58:16 ---> 1358556ef4ad
build 24-Jan-2015 22:58:16 Step 9 : COPY ./templates/php_modules/20-apc.ini /etc/php5/conf.d/20-apc.ini
build 24-Jan-2015 22:58:16 ---> 4b21637fa55b
build 24-Jan-2015 22:58:16 Removing intermediate container 3c2658197f2b
Second run on machine B:
build 25-Jan-2015 09:35:24 Step 8 : RUN cd /usr/local/src/APC-3.1.13; /usr/local/bin/phpize; ./configure --with-php-config=/usr/local/bin/php-config; make; make install
build 25-Jan-2015 09:35:24 ---> Using cache
build 25-Jan-2015 09:35:24 ---> 1358556ef4ad
build 25-Jan-2015 09:35:24 Step 9 : COPY ./templates/php_modules/20-apc.ini /etc/php5/conf.d/20-apc.ini
build 25-Jan-2015 09:35:24 ---> f77fe0b46890
build 25-Jan-2015 09:35:24 Removing intermediate container 473b3e831c87
Expected behaviour:
When file content not changed (as example md5 sum is the same) Docker has to use cached image.