docker - Dockerfile COPY instruction failing?

Question

All, i'm trying to persistently copy files from my host to an image so those files are available with every container launched based on that image. Running on debian wheezy 64bit as virtualbox guest.

the Dockerfile is fairly simple (installing octave image):

FROM debian:jessie 
MAINTAINER GG_Python <[redacted]@gmail.com>
RUN apt-get update 
RUN apt-get update
RUN apt-get install -y octave octave-image octave-missing-functions octave-nan octave-statistics

RUN mkdir /octave
RUN mkdir /octave/libs
RUN mkdir /octave/libs/jsonlab
COPY ~/octave/jsonlab/loadjson.m /octave/libs/jsonlab/.

I'm getting the following trace after issuing a build command: docker build -t octave .

Sending build context to Docker daemon 423.9 kB
Sending build context to Docker daemon 
Step 0 : FROM debian:jessie
 ---> 58052b122b60
Step 1 : MAINTAINER GG_Python <[..]@gmail.com>
 ---> Using cache
 ---> 90d2dd2f7ee8
Step 2 : RUN apt-get update
 ---> Using cache
 ---> 4c72c25cd829
Step 3 : RUN apt-get update
 ---> Using cache
 ---> b52f0bcb9f86
Step 4 : RUN apt-get install -y octave octave-image octave-missing-functions octave-nan octave-statistics
 ---> Using cache
 ---> f0637ab96d5e
Step 5 : RUN mkdir /octave
 ---> Using cache
 ---> a2d278b2819b
Step 6 : RUN mkdir /octave/libs
 ---> Using cache
 ---> 65efbbe01c99
Step 7 : RUN mkdir /octave/libs/jsonlab
 ---> Using cache
 ---> e41b80901266
Step 8 : COPY ~/octave/jsonlab/loadjson.m /octave/libs/jsonlab/.
INFO[0000] ~/octave/jsonlab/loadjson.m: no such file or directory 

Docker absolutely refuses to copy this file from the host into the image. Needless to say a the file loadjson.m is there (cat displays), all my attempts to change the path (relative, absolute, etc.) failed. Any advice why this simple task is problematic?

Answer 1

At the time I originally wrote this, Docker didn’t expand ~ or $HOME. Now it does some expansions inside the build context, but even so they are probably not what you want—they aren’t your home directory outside the context. You need to reference the file explicitly, or package it relative to the Dockerfile itself.