Installing libxml2 (xmllint) in node10.x runtime

Question

I have a lambda that uses node8.x we were recently notified that the lambda 8.x run-time is reaching EOL and we should upgrade to node 10.x.  That's all well and good, but I'm running into a problem.  My lambda uses a binary (xmllint) to validate XML, but the libxml2 (and shell command xmllint) are not available in the environment.    
  
I assume I should create a layer for this, but I'm not sure how to get the dynamic linked libraries to work.  Any suggestions?

I've created a docker file to compile libxml2 and zip the files into a layer

```
FROM amazon/lambda-build-node10.x

RUN yum -y upgrade && \
    yum -y install gcc \
                   python-devel \
                   libxml2-devel \
                   libxslt-devel \
                   wget \
                   which \
                   tar \
                   xz \
                   gzip \
                   make \
                   zip


RUN wget http://xmlsoft.org/sources/libxml2-2.9.10.tar.gz
RUN gunzip -c libxml2-2.9.10.tar.gz | tar xvf -

RUN mkdir -p /package && \
    mkdir -p /host

RUN cd libxml2-2.9.10 && \
    ./configure --prefix=/package \
                --disable-static \
                --with-python=/usr/bin/python3 && \
    make && \
    make install
```

After I create the layer and attach it to my lambda - When I invoke the lambda and shell out to xmllint I facing this error.  Any suggestions or ideas?

```
xmllint: error while loading shared libraries: liblzma.so.5: cannot open shared object file: No such file or directory
```

Answer

I've finally figured out the problem. I'm going to post here in case this is helpful to others. It was helpful to see the shared object files using the **ldd** command. After seeing this, I figured I cold resolve this by install **xz** from source and include that as part of the layer.  
  
Here are the steps I ran.  
  
1. Build the docker image - I gave it a tag of amzlinux2

```
$ docker build -t amzlinux2 .
```

2. Next, run the container

```
$ docker run -it --rm -v "$PWD":/host amzlinux2 bash
```

3. In the container we need to zip up the files so we can upload them as a layer

```
$ cd /opt && zip --symlinks -r /host/libxml2.zip ./*
```

4. At this point you'll have a libxml2.zip file on your host machine.  You can upload this as a layer and add it to your function.

**ldd**

```
$ ldd /opt/bin/xmllint    
    
linux-vdso.so.1 (0x00007ffcd9de0000)\    
libxml2.so.2 => /opt/lib/libxml2.so.2 (0x00007ffb7f28f000)\    
libdl.so.2 => /lib64/libdl.so.2 (0x00007ffb7f08b000)\    
libz.so.1 => /lib64/libz.so.1 (0x00007ffb7ee75000)\    
liblzma.so.5 => not found\    
libm.so.6 => /lib64/libm.so.6 (0x00007ffb7eb2a000)\    
libc.so.6 => /lib64/libc.so.6 (0x00007ffb7e774000)\    
/lib64/ld-linux-x86-64.so.2 (0x00007ffb7f5e1000)\    
liblzma.so.5 => not found\    
```

**Dockerfile**

```
FROM amazon/lambda-build-node10.x

RUN yum -y upgrade && \
    yum -y install gcc \
                   python-devel \
                   libxml2-devel \
                   libxslt-devel \
                   wget \
                   which \
                   tar \
                   gzip \
                   make \
                   zip


RUN wget http://xmlsoft.org/sources/libxml2-2.9.10.tar.gz
RUN gunzip -c libxml2-2.9.10.tar.gz | tar xvf -

RUN mkdir -p /host

RUN wget https://tukaani.org/xz/xz-5.2.4.tar.gz
RUN tar xvfz xz-5.2.4.tar.gz

RUN cd xz-5.2.4 && \
		./configure --prefix=/opt && \
    make && \
    make install

RUN cd libxml2-2.9.10 && \
    ./configure --prefix=/opt \
                --disable-static \
                --with-python=/usr/bin/python3 && \
    make && \
    make install
```

Installing libxml2 (xmllint) in node10.x runtime

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