mihalis's picture

Uncaught Error: Call to undefined function cache_get() in

If you get:

# drush up
PHP Fatal error: Uncaught Error: Call to undefined function cache_get() in

The solution might be as simple as executing the next command:
# sudo ln -sfn /usr/bin/php5 /etc/alternatives/php

Drupal 7

mihalis's picture

Save Docker image as a tar file

In this blog post I am going to tell you how to save a Docker image as a tar file and how to use that tar file afterwards.

First, you will need to have a Dockerfile:

$ cat Dockerfile
FROM golang:alpine
RUN mkdir /files
COPY hw.go /files
WORKDIR /files
RUN go build -o /files/hw hw.go
ENTRYPOINT ["/files/hw"]

Then, you will need to create a Docker image from that Dockerfile:

$ docker build -t go_hw:v1 .
Sending build context to Docker daemon 134.1kB
Step 1/6 : FROM golang:alpine
alpine: Pulling from library/golang
cd784148e348: Pull complete
7e273b0dfc44: Pull complete
952c3806fd1a: Pull complete
ee1f873f86f9: Pull complete
7172cd197d12: Pull complete
Digest: sha256:198cb8c94b9ee6941ce6d58f29aadb855f64600918ce602cdeacb018ad77d647
Status: Downloaded newer image for golang:alpine
---> f56365ec0638
Step 2/6 : RUN mkdir /files
---> Running in 6281fe42eb5b
Removing intermediate container 6281fe42eb5b
---> 8dd252caee51
Step 3/6 : COPY hw.go /files
---> a06ad8bf8b54
Step 4/6 : WORKDIR /files
---> Running in aaea454a1320
Removing intermediate container aaea454a1320
---> 512077e5d14d
Step 5/6 : RUN go build -o /files/hw hw.go
---> Running in e5474648eefe
Removing intermediate container e5474648eefe
---> 61e930e48a5a
Step 6/6 : ENTRYPOINT ["/files/hw"]
---> Running in f5ca2e84ada1
Removing intermediate container f5ca2e84ada1
---> 492dda632ae1
Successfully built 492dda632ae1
Successfully tagged go_hw:v1

After that you are ready to save that Docker image:

$ docker save go_hw:v1 -o go_hw.tar
$ ls -l go_hw.tar
-rw------- 1 mtsouk staff 319876096 Jan 6 20:26 go_hw.tar

After that you can distribute your Docker image any way you want and load it as follows:

$ docker load -i go_hw.tar
7bff100f35cb: Loading layer 4.672MB/4.672MB
b14874cfef59: Loading layer 838.7kB/838.7kB
789935042c6f: Loading layer 2.56kB/2.56kB
61b145086eb8: Loading layer 312.4MB/312.4MB
e121936484eb: Loading layer 2.56kB/2.56kB
c53a945a0db2: Loading layer 1.536kB/1.536kB
323c5d051144: Loading layer 2.56kB/2.56kB
ed9b85466379: Loading layer 1.93MB/1.93MB
Loaded image: go_hw:v1

The output of docker images will verify that the docker image is ready for use:

$ docker images
go_hw v1 492dda632ae1 3 minutes ago 312MB

mihalis's picture

Working with Kubernetes

Among other things I am currently working with Docker and Kubernetes. Both are really interesting and challenging subjects that I really enjoy!

The image of this blog post shows the output of an Apache web server running in Kubernetes!

$ kubectl get pods
nginx-2-6bd764c757-77rq9 1/1 Running 0 10s
nginx-2-6bd764c757-kbqd7 1/1 Running 0 10s
nginx-2-6bd764c757-srmds 1/1 Running 0 10s

mihalis's picture

Mastering Go for UNIX administrators, UNIX developers and Web Developers

You can find more about the Mastering Go for UNIX administrators, UNIX developers and Web Developers course here.

You still have time to register!

mihalis's picture

2nd Athens Gophers Meetup

I will talk at the 2nd Athens Gophers Meetup (Thursday 04 October 2018).
Subject: Go - Goroutines + Channels.
You can learn more about it at



Subscribe to RSS - blogs