I am new to docker. I created a docker file to run apt update and install dnsutils in the docker image, the build is successful. But when I run docker image and get the shell of the container, i dont find the tools installed. What wrong am I doning? Below is the docker file and output for reference.
#dockerfile
FROM debian
ENV DEBIAN_FRONTEND=noninteractive
RUN apt update && apt install -y dnsutils && rm -rf /var/lib/apt/lists/*
FROM php:7.0-apache
WORKDIR /var/www/html
COPY index.php index.php
EXPOSE 80
# docker build output
sudo docker build -t lookup-demo .
Sending build context to Docker daemon 3.584kB
Step 1/7 : FROM debian
latest: Pulling from library/debian
d836772a1c1f: Pull complete
Digest: sha256:2ce44bbc00a79113c296d9d25524e15d423b23303fdbbe20190d2f96e0aeb251
Status: Downloaded newer image for debian:latest
---> 123c2f3835fd
Step 2/7 : ENV DEBIAN_FRONTEND=noninteractive
---> Running in c030e13e5c4d
Removing intermediate container c030e13e5c4d
---> 64f8a1b2f607
Step 3/7 : RUN apt update && apt install -y dnsutils && rm -rf /var/lib/apt/lists/*
---> Running in 7b35c913afa7
WARNING: apt does not have a stable CLI interface. Use with caution in scripts.
Get:1 http://deb.debian.org/debian bullseye InRelease [116 kB]
Get:2 http://deb.debian.org/debian-security bullseye-security InRelease [44.1 kB]
--SNIPPED--
Fetched 8550 kB in 6s (1486 kB/s)
Reading package lists...
Building dependency tree...
Reading state information...
All packages are up to date.
WARNING: apt does not have a stable CLI interface. Use with caution in scripts.
Reading package lists...
Building dependency tree...
Reading state information...
The following additional packages will be installed:
bind9-dnsutils bind9-host bind9-libs libbsd0 libedit2 libfstrm0 libicu67
libjson-c5 liblmdb0 libmaxminddb0 libmd0 libprotobuf-c1 libuv1 libxml2
Suggested packages:
mmdb-bin
The following NEW packages will be installed:
bind9-dnsutils bind9-host bind9-libs dnsutils libbsd0 libedit2 libfstrm0
libicu67 libjson-c5 liblmdb0 libmaxminddb0 libmd0 libprotobuf-c1 libuv1
libxml2
0 upgraded, 15 newly installed, 0 to remove and 0 not upgraded.
Need to get 12.2 MB of archives.
After this operation, 42.3 MB of additional disk space will be used.
Get:1 http://deb.debian.org/debian bullseye/main amd64 libfstrm0 amd64 0.6.0-1+b1 [21.5 kB]
--SNIPPED-- ...
Setting up bind9-dnsutils (1:9.16.27-1~deb11u1) ...
Setting up dnsutils (1:9.16.27-1~deb11u1) ...
Processing triggers for libc-bin (2.31-13+deb11u3) ...
Removing intermediate container 7b35c913afa7
---> e06841ed6429
Step 4/7 : FROM php:7.0-apache
---> aa67a9c9814f
Step 5/7 : WORKDIR /var/www/html
---> Running in f23042e65327
Removing intermediate container f23042e65327
---> 2d99a8d80b10
Step 6/7 : COPY index.php index.php
---> d7a6b1478f79
Step 7/7 : EXPOSE 80
---> Running in 2b873b46e964
Removing intermediate container 2b873b46e964
---> 5c8964ef0a4e
Successfully built 5c8964ef0a4e
Successfully tagged lookup-demo:latest
# output from the shell
sudo docker exec -it 1cd5f6b568cf bash
root@1cd5f6b568cf:/var/www/html# nslookup
bash: nslookup: command not found