Issue installing zdns inside Docker

[gorums]

Dockerfile

---

RUN apt-get update && apt-get install -y git wget unzip

Install Golang

RUN wget https://golang.org/dl/go1.16.linux-amd64.tar.gz
RUN tar -C /usr/local -xzf go1.16.linux-amd64.tar.gz
RUN export GOPATH=$HOME/go
RUN export PATH=$PATH:/usr/local/go/bin:$GOPATH/bin

RUN git clone https://github.com/zmap/zdns.git
RUN cd zdns/zdns && /usr/local/go/bin/go build

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Output:
Step 31/32 : RUN cd zdns/zdns && /usr/local/go/bin/go build
---> Running in 602369823d69
go: github.com/miekg/dns@v1.1.27 (replaced by github.com/zmap/dns@v1.1.35-zdns-2): missing go.sum entry; to add it:
go mod download github.com/miekg/dns

[stklcode]

Missing update of the go.sum file. Since Go 1.16 modules are no longer updated automatically (up to 1.15 it builds fine). The solution is the last line of the output:

go mod download github.com/miekg/dns

Simply run this command inside the project root before the “go build“ step like

RUN cd zdns && \
    /usr/local/go/bin/go mod download github.com/miegk/dns && \
    cd zdns && \
    /usr/local/go/bin/go build

Committing the the updated go.sum resolves the problem permanently.